Average Weather in Nantucket Massachusetts, United States
In Nantucket, the summers are comfortable, humid, and windy; the winters are chilly, wet, and extremely windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 26°F to 75°F and is rarely below 14°F or above 81°F.
The warm season lasts for 3.3 months, from June 14 to September 24, with an average daily high temperature above 68°F. The hottest day of the year is July 30, with an average high of 75°F and low of 65°F.
The cold season lasts for 3.4 months, from December 12 to March 24, with an average daily high temperature below 46°F. The coldest day of the year is January 30, with an average low of 26°F and high of 38°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
In Nantucket, 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 Nantucket begins around June 25 and lasts for 4.6 months, ending around November 12. On September 6, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 62% of the time, and overcast or mostly cloudy 38% of the time.
The cloudier part of the year begins around November 12 and lasts for 7.4 months, ending around June 25. On May 15, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Nantucket varies throughout the year.
The wetter season lasts 10 months, from July 31 to June 4, with a greater than 26% chance of a given day being a wet day. The chance of a wet day peaks at 31% on December 11.
The drier season lasts 1.9 months, from June 4 to July 31. The smallest chance of a wet day is 20% on July 4.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 30% on April 12.
Daily Chance of Precipitation
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. Nantucket experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year in Nantucket. The most rain falls during the 31 days centered around November 28, with an average total accumulation of 3.9 inches.
The least rain falls around July 8, with an average total accumulation of 2.3 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Nantucket experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 3.5 months, from December 13 to March 27, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around February 6, with an average total liquid-equivalent accumulation of 0.4 inches.
The snowless period of the year lasts for 8.5 months, from March 27 to December 13. The least snow falls around July 31, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Nantucket varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 12 minutes of daylight; the longest day is June 21, with 15 hours, 10 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:06 AM on June 14, and the latest sunrise is 2 hours, 9 minutes later at 7:15 AM on November 4. The earliest sunset is at 4:11 PM on December 8, and the latest sunset is 4 hours, 7 minutes later at 8:17 PM on June 26.
Daylight saving time (DST) is observed in Nantucket during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
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.
Nantucket experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 3.0 months, from June 23 to September 24, during which time the comfort level is muggy, oppressive, or miserable at least 13% of the time. The muggiest day of the year is August 2, with muggy conditions 53% of the time.
The least muggy day of the year is December 12, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
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 Nantucket experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 6.4 months, from October 10 to April 21, with average wind speeds of more than 8.3 miles per hour. The windiest day of the year is January 13, with an average hourly wind speed of 10.5 miles per hour.
The calmer time of year lasts for 5.6 months, from April 21 to October 10. The calmest day of the year is July 25, with an average hourly wind speed of 6.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Nantucket varies throughout the year.
The wind is most often from the south for 2.9 months, from June 23 to September 21, with a peak percentage of 41% on July 14. The wind is most often from the west for 9.1 months, from September 21 to June 23, with a peak percentage of 45% on January 1.
Nantucket 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 3.1 months, from June 30 to October 2, with an average temperature above 61°F. The day of the year with the warmest water is August 11, with an average temperature of 67°F.
The time of year with cooler water lasts for 3.9 months, from December 28 to April 25, with an average temperature below 45°F. The day of the year with the coolest water is February 28, with an average temperature of 39°F.
Average Water Temperature
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 3.3 months, from May 7 to August 17, with an average daily incident shortwave energy per square meter above 6.0 kWh. The brightest day of the year is June 30, with an average of 7.1 kWh.
The darker period of the year lasts for 3.4 months, from November 4 to February 14, with an average daily incident shortwave energy per square meter below 2.8 kWh. The darkest day of the year is December 26, with an average of 1.7 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Nantucket are 41.283 deg latitude, -70.099 deg longitude, and 13 ft elevation.
The topography within 2 miles of Nantucket is essentially flat, with a maximum elevation change of 69 feet and an average elevation above sea level of 18 feet. Within 10 miles is also essentially flat (92 feet). Within 50 miles is essentially flat (358 feet).
The area within 2 miles of Nantucket is covered by artificial surfaces (49%), water (34%), and trees (13%), within 10 miles by water (86%), and within 50 miles by water (92%).
This report illustrates the typical weather in Nantucket, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Nantucket.
For each station, the records are corrected for the elevation difference between that station and Nantucket according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Nantucket is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Nantucket and a given station.
The stations contributing to this reconstruction are: Nantucket Memorial Airport (91%, 4.7 kilometers, southeast); Martha's Vineyard Airport (3.2%, 45 kilometers, west); Barnstable Municipal Airport-Boardman/Polando Field (3.1%, 45 kilometers, north); and Chatham Municipal Airport (3.0%, 46 kilometers, north).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.