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NYC (KLGA) Climatology for March

During my time taking classes as part of Penn State University’s Undergraduate Certificate in Weather Forecasting, we were taught that understanding the climatology of the location you are interested in is an important prerequisite for making accurate forecasts. As such, I’ve decided to post some critical components of climatology for the closest station to me, LaGuardia Airport (KLGA). Below, I’ve posted some general climate data, and also specific data for the month of March.

Other Month’s Climatologies

January
February
April
May
June
July
August
September
October
November
December

Station Basic Information

City Name / Station ID: New York, NY (LaGuardia Airport – KLGA)

Local Geography and Topography

Station Elevation: 10 feet above sea level.

Station Location: LaGuardia Airport (KLGA) is situated on the north shore of Queens along the East River, approximately 6 miles east-northeast of Midtown Manhattan.

KLGA’s location within the broader NYC area, as seen in a Google Maps terrain view

Important Topographical Features: New York City is located in the extreme southeastern corner of New York State, bordering suburban New Jersey and Connecticut. These suburban regions combined with those in Long Island comprise the Greater New York City Metropolitan Area, which is the most populous urban agglomeration in the United States and one of the populous urbanized areas in the world with an estimated population of 18 million. New York City itself sprawls across the coastal plain around the Hudson River estuary. The terminal moraine formed by glaciers of the last Ice Age result in a ridge of higher terrain that cuts a swath from southwest to northeast across the boroughs from northern Staten Island, northern Brooklyn, southwestern through central and northeastern Queens. Otherwise, the city itself is low lying. This ridge varies in height between 200-400 feet, rising sharply from south to north, but tapering more gently north. North and west of the city (about 30-50 miles away), lie significant elevations of the Catskills (north), Poconos (west), Taconics that are part of the broader Appalachian Mountain Range. The elevations of the lower foothills can range from 1000-1500 feet. Some of the elevations in the Poconos and Catskills, west and north of KLGA respectively, peak between 2000-3000 feet. The open expanse of the Atlantic Ocean lies south of KLGA and New York City. Long Island Sound also lies east-northeast. The vast urbanized area of the NYC metropolitan region has significant effects on local microclimates via differential heating (urban heat island effect). KLGA is in a low-lying area sensitive to UHI effects and marine influences.

Topographical map of New York State

Per the Local Climatological Data report from the National Weather Service:

On winter mornings, ocean temperatures which are warm relative to the land reinforce the effect of the city heat island and low temperatures are often 10-20 degrees lower in the inland suburbs than in the central city. The relatively warm water temperatures also delay the advent of winter snows. Conversely, the lag in warming of water temperatures keeps spring temperatures relatively cool. One year-round measure of the ocean influence is the small average daily variation in temperature.

National Weather Service – NYC Office

Wind Patterns

Below is a wind rose – you can read more about how to interpret this chart here.

March wind rose for KLGA, source: National Resource Conservation Service

Frequency (percentage) of the single most common wind direction: Due northwest occuring about 14% of the time.

Directions that are most and least common: Most common wind directions following due northwest are due northeast (11.75%), west-northwest (10.25%), north-northwest (8.5%). Least common wind directions are east-southeast (1%), due southeast (2%), and due east (2.25%).

Direction(s) most likely to produce the fastest winds: The most common wind directions are also the ones most likely to produce the fastest winds.

Direction(s) least likely to produce the fastest winds: Again, the least common wind directions are also least likely to produce the fastest winds.

Impacts of wind direction on local weather: Prevalent northwesterly winds during this month generally follow in the wake of cold fronts and coastal storms. These winds can lead to substantial cold air advection (transport of cold, dry continental polar air mass from interior Canada), often because of subsidence in the wake cold fronts mixing down very fast winds to the surface. These winds will downslope and warm slightly as they approach the coast though. A secondary maximum of winds from the northeast can be attributed to backdoor cold fronts arriving from the Canadian Maritimes, bringing a moist, cool maritime polar air mass, or in conjunction with the advance of coastal Nor’easter type storms. During March, sea surface temperatures in the vicinity of NYC are above freezing, but by no means warm. If a warmer air mass is in place prior to winds shifting to the northeast, cooler, more moist conditions will result. If a colder, below freezing air mass is present, northeasterly winds can exert moderating influence on temperatures. Persistent northeasterly winds can also lead to the potential for coastal flooding given the shape of local coastline.

Maximum observed two-minute wind speed for the month in knots: 40 knots (46 mph).

Temperature and Precipitation Averages/Records

Temperature units are in Fahrenheit and precipitation is in inches.

Worth Noting: Average temperatures in March rise above 50°F for the first month since November. However, March can certainly still produce cold days – many of the record lowest max temperatures are below freezing, with record lows still in the teens and single digits. It is a month indicative of spring when large temperature swings are possible.

DateNormal HighNormal LowRecord HighRecord LowRecord Lowest MaxRecord Highest MinNormal PrecipRecord Precip
1453171825530.122.23
24631671325500.112.44
34631651025490.122.26
4463169725460.111.53
5463272925480.120.72
64732641424480.122.47
74732691425490.131.90
84732741428540.121.20
94733751426490.122.18
104833781227620.121.52
114833701530490.121.40
124833691528490.121.83
134934831933530.123.15
144934751834500.121.41
154934741429480.131.61
165034771932510.131.12
175035741526540.131.39
185035751319510.142.05
195135721026530.131.38
205136821931530.141.18
215136701834530.142.00
225236761933540.133.15
235237741926560.141.44
245237741730500.141.63
255337771832500.131.55
265338722034510.141.26
275438832336540.141.20
285438832336580.132.83
295439862534590.141.90
305539792334590.132.65
315539822436590.142.10
Range45-5531-3964-867-2519-3645-620.11-0.140.72-3.15





NYC Weekend Weather – Mar 1, 2019

Although the calendar has flipped to March and we’re less than 3 weeks from the official start of spring, the weather has taken a decidedly winter-like turn as of late. This pattern will continue over the weekend and into next week. Initially, we’ll contend with 2 coastal storms that will bring chances for snow, and then enter next week with temperatures well below normal for this time of year. Sadly, this colder than normal pattern looks locked in for the next week or more

Rest of today – overcast conditions with temperatures hovering in the mid-30s. Precipitation will move back into the area by later this evening. Thermal profiles overnight point to a mix of snow/sleet at the coast with lows just around freezing. The local forecast office calls for an accumulation of 1-2″ of this wintry mess.

Weather Prediction Center surface forecast for 7AM Saturday

Saturday – the wintry precipitation continues the first half of the day as the first of two coastal storms continues to impact the region. High temperatures should warm up to around 40ºF with mostly cloudy skies, and precipitation should die off later in the day. Overnight lows should be around freezing.

Sunday – starts off as a decent enough day, but a second storm will be brewing and moving offshore, impacting the area overnight into Monday. High temperatures should be similar to Saturday in the low-40s with partly sunny skies. At this point, the primary precipitation modes at the coast appears to be a rain/snow mix. Thermal profiles don’t appear cold enough to support all snow with overnight lows expected to be above freezing around 35ºF.

Global Forecast System 1000 mb – 500 mb height, pressure, thickness foreast for 6AM Monday

Monday – precipitation tapering off early in the morning as this storm is a fast-mover. Temperatures topping out in the upper-30s with mostly cloudy skies.

Colder than Normal Temperatures Ahead

Climate Prediction Center has a 6-10 day temperature outlook suggesting a colder than normal pattern for much of the country, including our area. During this time, the polar jet stream is expected to dip further south allowing colder air to penetrate into the Continental US.

NYC Weekend Weather – Feb 8, 2019

A mild start to this weekend will transition quickly to colder temperatures more typical of this the of year. A windy day in store on Saturday in the wake of a cold front bringing us rain today. cold temperatures remain in place into the beginning of next week. No more 60°F+ days in store for us!

Rest of today – rain tapering off by around lunchtime. Mild temperatures with highs in the mid-50s with clearing conditions. Once the cold front sweeps through, winds will pick up from west into the 15-20 mph range. This will advect cold air into the area and overnight lows are forecast in the mid-20s. By midnight, temperatures will be around the freezing mark.

Weather Prediction Center’s surface forecast for 7PM tonight

Saturday – a windy day on tap with much colder high temperatures in the mid-30s. Winds expected in the 15-20 mph range with strong gusts around 35 mph. Overnight lows again in the mid-20s.

Sunday – winds abate as the low responsible for the rain today moves further off. High temperatures in the mid-30s with mostly sunny skies. Overnight low around 30°F, with a small chance of snow showers.

Monday – increasing clouds ahead of the next storm system that could bring us some wintry weather Tuesday. High temperatures in the low-40s. Overnight lows in the upper-30s.

NYC Lunar New Year Weather Update, Feb 4, 2019

What a difference a week makes. Last week, we saw some of the coldest air to hit NYC in quite a while. This week, we’ll have the chance to hit 60°F. Two low pressure systems will impact the area, the first is not forecast to produce precipitation, while the second will likely bring rain. Both of these lows will bring a surge of warm air in their warm sectors prior to the passage of the trailing cold front accompanying them. Enjoy the balmy February weather while you can, because the warmth won’t last.

Rest of today – mostly sunny with high temperatures reaching into the low-50s. Patchy fog developing overnight with low temperatures near 40°F.

Tuesday (Lunar New Year)– a mild start to the day gives us a shot to reach into the upper-50s. We’ll be in the warm sector of the first low. If a deck of low clouds builds in and persists, we might be a bit cooler in the mid-50s. On the other hand, if we get a relatively sunny day instead we could see high temperatures around 60°F. Overnight lows considerably cooler around 30°F with a dry cold frontal passage from this first low pressure system.

Weather Prediction Center’s surface forecast for 7PM Tuesday, showing the “dry” passage of a cold front

Wednesday – a cooler start to the day should result in temperatures only reaching the low-40s. Clouds increasing, and rain expected to develop overnight into Thursday with low temperatures in the mid-30s.

Thursday – a few degrees warmer with high temperatures in the mid-40s and rain. Rain expected to taper off a bit after the warm front associated with the second low to hit us moves north of the area. This will set us up for a warm day on Friday as well. Overnight lows going into Friday not much cooler than day time highs, in the low-40s.

NYC Weekend Weather – Jan 25, 2019

A quiet, and mostly dry weekend is on tap after a wet and windy day yesterday. This will be a welcome change of pace from the active weather pattern we’ve seen on prior weekends. There isn’t any precipitation expected and temperatures are forecast to alternate between the low-40s and low-30s. The next chance for meaningful precipitation comes Tuesday.

Rest of today – high temperatures near 40ºF, partly sunny with winds picking up in the afternoon. Overnight lows will be much cooler in the wake of a dry cold front passing through around 20ºF.

Saturday – high pressure will be in control for the day, but it’ll be a cold day with high temperatures topping out in the low-30s under partly sunny skies. Overnight lows warmer in the upper-20s as the high pressure center moves off to the east and winds shift to the south.

Sunday – temperatures warm into the low-40s with return flow from the south on the west side of the departing high. Overnight lows will be similar to Saturday in the upper-20s.

Weather Prediction Center surface forecast for 7AM Sunday

Monday – things turn colder again in the wake of another cold front passing through with high temperatures in the low-30s with partly cloudy skies.

NYC Weekend Weather – Jan 11, 2019

We’ll have a cold weekend ahead, however, we will dodge a bullet with a major winter storm tracking to our south. The northern fringes of this system could still bring some light snow to the city, though. The cold temperatures stay in place through the weekend and into early next week. Looking ahead, we should see a pattern change that leads to some warmer temperatures by mid-week next week

Rest of today – mostly sunny, cold, with high temperatures hovering around 30°F. Gusty northwest winds steadily subsiding as a strong Arctic high pressure center moves closer to us. Clear, crisp night with overnight lows around 20°F.

Saturday – partly sunny, high temperatures topping out around the freezing mark. Snow flurries are possible overnight into Sunday. Overnight lows in the mid-20s.

Weather Prediction Center surface forecast for Saturday at 7AM. Note the strong Arctic high pressure to our north, 1040 mb, which will effectively block the winter storm to the south from heavily impacting this region.

Sunday – partly sunny with clouds possibly breaking from north to south later in the day. Some flurries still possible early in the day. High temperatures similar to Saturday around freezing. Overnight lows in the low-20s.

Monday – mostly sunny, with high pressure building again, temperatures still cold in the mid-30s.

NYC Weekend Weather – Jan 4, 2019

The first weekend of 2019 holds a mixed bag for NYC. Saturday looks to be a rainy day, while Sunday should shape up to be a pleasant, milder day, though not nearly as warm as New Year’s Day. Going into next week, another storm system approaches and may bring precipitation as early as Monday evening. This weekend, I’ll have a follow up post regarding the high likelihood of El Nino developing in the Pacific this winter, and what implications this could have for tangible weather this season in our region.

Rest of today – Increasing clouds. High temperatures in the mid-40s. Overnight, rain starts to move in ahead of an approaching warm front associated with a surface low tracking east and offshore of the Delmarva Peninsula. Overnight lows around 40.

Weather Prediction Center surface forecast for 7AM Saturday. With a warm front positioned to our south, persistent northeasterly onshore winds will present a possible issue for coastal flooding, and keep temperatures suppressed.

Saturday – rain for the bulk of the morning and the afternoon hours. Cooler, with onshore flow north of the warm front mentioned above. Temperatures topping out in the low-40s. Rain tapering off towards the late evening hours, then skies steadily clearing with overnight lows in the mid-30s.

Sunday – bright, sunny day on tap behind the storm system Saturday day. Temperatures a touch warmer in the mid-40s. Overnight lows into Monday dropping into the low-30s as a cold front moves through. No precipitation anticipated with this cold front at this time.

GFS model output for Monday at 5PM. By this time, we’re forecast to be under an area of high pressure, but wedged between the departing weekend storm and the next storm approaching form our west.

Monday – increasing clouds ahead of the next storm system. Temperatures in the mid-30s with colder air in place behind the cold front mentioned above. Overnight lows holding steady, dropping a couple degrees maybe – another warm front will help stabilize temperatures as rain or a rain/snow mix develops. Exact precipitation type is difficult to determine at this time.

NYC New Year’s Eve Weather – Dec 31, 2018

New Year’s Eve this year looks like a washout, but temperatures will be very mild. In fact temperatures will maintain a non-diurnal trend, warming through the night. New Year’s Day could see the possibility of record warmth before a return to more normal conditions mid-week. Another storm system approaches for the end of the week.

Rest of today – cloudy with high temperatures in the upper-40s. A warm front approaching from the south and west will start to bring steady rain to the area by late afternoon. A favorable low-level jet, along with robust isentropic lift (overrunning of warm air above cold air along the warm front) should enable plenty of moisture and enough instability to trigger bouts of heavy rain later in the evening and overnight. Unfortunately, the bulk of rain looks to fall right during periods when revelers will be out on the town celebrating the new year. Winds will pick up as well with the pressure gradient tightening and efficient downward momentum transfer of low-level jet winds during periods of precipitation. As mentioned above, temperatures will follow a non-diurnal trend, with the warm front and warm sector of this storm advecting milder air from the southeast. Temperatures will actually rise into the mid-50s overnight.

NAM (North American Model) forecast of 850 mb relative humidity and winds for 10PM tonight. The blue hues indicate saturated air, while we can see some wind barbs showing winds > 60 knots. These are classic signs of a low-level jet that is often implicated in producing heavy precipitation events.
Weather Prediction Center surface forecast for 7AM Tuesday. Note the tight packing of isobars (black lines) around the parent low that’s going to bring us rain. This indicates a tight pressure gradient that will drive strong winds. This surface forecast also suggests that our time in the warm sector of this low (outlined in light orange above) will be brief. Warm advection (transport of warm air) won’t last long into Tuesday.

Tuesday (New Year’s Day) – I’ll follow up with a detailed forecast, the start of 2019 will be quite interesting for a couple reasons, one being possible record warmth and the other being strong, gusty winds. Temperatures will be rising throughout the night into Tuesday such that high temperatures will peak early in the day. Depending on exactly when this happens, temperatures could push above 60ºF, which would be nearing or exceeding records. The record high for January 1st at Central Park is 62ºF set in 1966. A lot will hinge on whether clouds clear up early enough to allow for a few hours of solid sunshine. This warmth will be short-lived though, because we won’t spend that much time in the warm sector of this parent low. As a trailing cold front moves through, winds will shift to the northwest and result in cold advection. As a result, temperatures will be falling during the day into the upper-40s by sunset. Temperatures are forecast to continue dropping overnight into Wednesday with lows bottoming out around freezing in the city.

Wednesday – a rude awakening to normal temperatures for this time of year. There will be a cold start to the day with high temperatures 20ºF cooler than Tuesday, in the upper-30s. Partly cloudy skies. Overnight lows in the mid-30s.

Thursday – warmer than Wednesday with another storm system approaching. So far, looking at a mostly cloudy day with highs in the low-40s. Rain may start as early as the overnight hours. A lot of uncertainty still at this time with the timing, scope, and precipitation type of this next storm though.

NYC Weekend Weather – Dec 28, 2018

The last weekend of the year gets off to a mild, rainy start as a storm system moves through. Things cool off and dry out the remainder of the weekend but it looks like another rain event and warm spell hits for New Year’s Eve.

Rest of today – rain through most of the day. Gusty winds around 30 mph possible. High temperatures well above normal in the mid-50s due to a surge of warm advection accompanying the warm front initially responsible for widespread rain. At the 850 mb level, a low-level jet develops, helping enhance moisture convergence and allow for heavier rains. A flood watch is actually in effect for areas of New Jersey in the metro NYC region. Lows going into Saturday will be quite warm in the mid-40s.

Storm Prediction Center mesoanalysis of 850 mb moisture transport. The maroon vectors indicate the magnitude and direction of moisture transport. The long vectors over the NYC region show efficient moisture transport due fast moving winds of a low-level jet at the 850 mb level. The shaded contours show values of theta-e (equivalent potential temperature), while the details of this are quite complex, the easiest way to understand theta-e is that high values indicate very moist airmasses that can be prime for development of convective activity, as an example. In this case, we can tell that the potential for heavy rain exists within areas of high theta-e (dark-green to red shaded areas).

Saturday – a strong cold front will move through during the afternoon which should result in high temperatures peaking early in the day around 50°F, even though it will remain mostly sunny all day. Behind this cold front, Canadian high pressure builds yielding much colder overnight lows into Sunday in the low-30s.

Weather Prediction Center surface forecast for Sunday at 7AM EST.

Sunday – much colder day on tap with Canadian high pressure in control. High temperatures around normal for this time of year near 40ºF even with plenty of sun. Overnight lows into Monday are forecast in the mid-30s.

Monday (New Year’s Eve) – clockwise return flow from the southwest on the western side of the exiting high pressure warms temperatures up into the upper-40s ahead of the next storm. The timing of this storm looks like it will result in a rainy New Year’s Eve in the city. This may sound less than ideal, but recall that we rang 2018 in with near record cold. It’ll be downright balmy in comparison this time with overnight lows forecast to barely budge in the mid-40s.

NYC Weather Update – Dec 10, 2018

This week features a continuation of the same general pattern we’ve experienced over the past week with below normal temperatures and no precipitation to speak of. Temperatures will remain cold through the majority of the work week until a pattern change this weekend brings a return of more seasonable (and even above average) temperatures along with the potential for a coastal storm that is expected to bring be all rain.

Rest of today – sunny and cold with high temperatures topping out around 40°F.Overnight lows quite chilly in the upper-20s to 30°F in the city. Clear skies and calm winds expected, giving rise to excellent conditions for radiational cooling.

Tuesday – very similar profile to today, another mostly sunny to sunny day with high temperatures in the upper-30s. More clouds expected overnight should help offset some radiational cooling, but still cold with lows around 30°F again.

500 mb longwave trough over the Eastern US, resulting in some colder than normal temperatures

Wednesday – broken record type of forecast here, yet another day of temperatures in the upper-30s. There’s more potential for cloud cover with this day due to the influence of a cold front which is forecast to move through. At this time, it doesn’t look like there’s enough moisture in the atmosphere for this to trigger snow showers. Cold again overnight with a reinforcing shot of Canadian air associated with a high pressure center behind this cold front. Lows in the mid-20s overnight.

Weather Prediction Center surface forecast for Wednesday morning, showing a cold front moving through our area

Thursday – partly sunny with high temperatures yet again hovering near 40°F. Overnight lows will be warmer in the mid-30s going into Friday than the rest of the week with return flow from the southwest behind the high pressure referenced above moving southeast into the Atlantic.