Climate and Average Weather Year Round in Long Island United States

In Long Island, the summers are warm and humid; the winters are very cold, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 23°F to 81°F and is rarely below 9°F or above 88°F.

Based on the tourism score, the best time of year to visit Long Island for warm-weather activities is from mid June to late September.

The warm season lasts for 3.4 months, from June 6 to September 18, with an average daily high temperature above 72°F. The hottest month of the year in Long Island is July, with an average high of 80°F and low of 64°F.

The cold season lasts for 3.3 months, from December 6 to March 16, with an average daily high temperature below 47°F. The coldest month of the year in Long Island is January, with an average low of 24°F and high of 39°F.

In Long Island, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year in Long Island begins around June 26 and lasts for 4.5 months, ending around November 11.

The clearest month of the year in Long Island is September, during which on average the sky is clear, mostly clear, or partly cloudy 62% of the time.

The cloudier part of the year begins around November 11 and lasts for 7.5 months, ending around June 26.

The cloudiest month of the year in Long Island is February, during which on average the sky is overcast or mostly cloudy 52% of the time.

Long Island does not experience significant seasonal variation in the frequency of wet days (i.e., those with greater than 0.04 inches of liquid or liquid-equivalent precipitation). The frequency ranges from 22% to 31%, with an average value of 27%.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Long Island is May, with an average of 8.8 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 30% on May 30.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Long Island experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year in Long Island. The month with the most rain in Long Island is April, with an average rainfall of 3.8 inches.

The month with the least rain in Long Island is January, with an average rainfall of 2.7 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Long Island experiences significant seasonal variation in monthly snowfall.

The snowy period of the year lasts for 4.5 months, from November 21 to April 6, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Long Island is January, with an average snowfall of 5.4 inches.

The snowless period of the year lasts for 7.5 months, from April 6 to November 21. The least snow falls around July 26, with an average total accumulation of 0.0 inches.

The length of the day in Long Island varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 15 minutes of daylight; the longest day is June 20, with 15 hours, 6 minutes of daylight.

The earliest sunrise is at 5:20 AM on June 13, and the latest sunrise is 2 hours, 4 minutes later at 7:24 AM on November 2. The earliest sunset is at 4:24 PM on December 6, and the latest sunset is 4 hours, 4 minutes later at 8:27 PM on June 26.

Daylight saving time (DST) is observed in Long Island during 2024, starting in the spring on March 10, lasting 7.8 months, and ending in the fall on November 3.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Long Island experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.4 months, from June 11 to September 25, during which time the comfort level is muggy, oppressive, or miserable at least 14% of the time. The month with the most muggy days in Long Island is July, with 14.8 days that are muggy or worse.

The least muggy day of the year is February 27, when muggy conditions are essentially unheard of.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Long Island experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.1 months, from October 6 to April 11, with average wind speeds of more than 11.9 miles per hour. The windiest month of the year in Long Island is January, with an average hourly wind speed of 14.8 miles per hour.

The calmer time of year lasts for 5.9 months, from April 11 to October 6. The calmest month of the year in Long Island is July, with an average hourly wind speed of 9.0 miles per hour.

The predominant average hourly wind direction in Long Island varies throughout the year.

The wind is most often from the south for 5.0 months, from April 28 to September 28, with a peak percentage of 42% on July 27. The wind is most often from the west for 7.0 months, from September 28 to April 28, with a peak percentage of 44% on January 1.

Long Island is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences significant seasonal variation over the course of the year.

The time of year with warmer water lasts for 3.4 months, from June 25 to October 5, with an average temperature above 65°F. The month of the year in Long Island with the warmest water is August, with an average temperature of 71°F.

The time of year with cooler water lasts for 3.7 months, from December 31 to April 19, with an average temperature below 45°F. The month of the year in Long Island with the coolest water is February, with an average temperature of 39°F.

To characterize how pleasant the weather is in Long Island throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Long Island for general outdoor tourist activities is from mid June to late September, with a peak score in the last week of August.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Long Island for hot-weather activities is from early July to late August, with a peak score in the last week of July.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Long Island typically lasts for 6.0 months (183 days), from around April 26 to around October 25, rarely starting before April 4 or after May 16, and rarely ending before October 8 or after November 12.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Long Island should appear around April 28, only rarely appearing before April 16 or after May 9.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.7 months, from April 29 to August 18, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest month of the year in Long Island is June, with an average of 6.9 kWh.

The darker period of the year lasts for 3.2 months, from November 4 to February 12, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest month of the year in Long Island is December, with an average of 1.8 kWh.

For the purposes of this report, the geographical coordinates of Long Island are 40.817 deg latitude, -73.066 deg longitude, and 0 ft elevation.

The topography within 2 miles of Long Island is essentially flat, with a maximum elevation change of 0 feet and an average elevation above sea level of 0 feet. Within 10 miles is also essentially flat (0 feet). Within 50 miles is also essentially flat (0 feet).

The area within 2 miles of Long Island is covered by artificial surfaces (100%), within 10 miles by artificial surfaces (67%) and water (18%), and within 50 miles by water (61%) and artificial surfaces (19%).