Average Weather at Plymouth United Kingdom
At Plymouth, the summers are comfortable; the winters are long, very cold, and wet; and it is windy and partly cloudy year round. Over the course of the year, the temperature typically varies from 39°F to 67°F and is rarely below 31°F or above 74°F.
Based on the tourism score, the best time of year to visit Plymouth for warm-weather activities is from late June to early September.
The warm season lasts for 3.0 months, from June 17 to September 18, with an average daily high temperature above 63°F. The hottest day of the year is July 29, with an average high of 67°F and low of 57°F.
The cool season lasts for 4.1 months, from November 23 to March 26, with an average daily high temperature below 51°F. The coldest day of the year is February 18, with an average low of 39°F and high of 47°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
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
At Plymouth, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year at Plymouth begins around March 30 and lasts for 6.5 months, ending around October 14. On July 24, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 57% of the time, and overcast or mostly cloudy 43% of the time.
The cloudier part of the year begins around October 14 and lasts for 5.5 months, ending around March 30. On December 25, the cloudiest day of the year, the sky is overcast or mostly cloudy 66% of the time, and clear, mostly clear, or partly cloudy 34% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days at Plymouth varies throughout the year.
The wetter season lasts 4.7 months, from October 1 to February 22, with a greater than 34% chance of a given day being a wet day. The chance of a wet day peaks at 46% on January 6.
The drier season lasts 7.4 months, from February 22 to October 1. The smallest chance of a wet day is 22% on July 24.
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 45% on January 6.
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. Plymouth experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year at Plymouth. The most rain falls during the 31 days centered around December 30, with an average total accumulation of 3.9 inches.
The least rain falls around July 22, with an average total accumulation of 1.8 inches.
Average Monthly Rainfall
The length of the day at Plymouth varies extremely over the course of the year. In 2018, the shortest day is December 21, with 8 hours, 1 minute of daylight; the longest day is June 21, with 16 hours, 26 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:04 AM on June 17, and the latest sunrise is 3 hours, 12 minutes later at 8:16 AM on December 31. The earliest sunset is at 4:12 PM on December 12, and the latest sunset is 5 hours, 19 minutes later at 9:31 PM on June 25.
Daylight saving time (DST) is observed at Plymouth during 2018, starting in the spring on March 25, lasting 7.1 months, and ending in the fall on October 28.
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.
The perceived humidity level at Plymouth, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.
Humidity Comfort Levels
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 at Plymouth experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 5.5 months, from October 11 to March 28, with average wind speeds of more than 14.5 miles per hour. The windiest day of the year is January 1, with an average hourly wind speed of 17.6 miles per hour.
The calmer time of year lasts for 6.5 months, from March 28 to October 11. The calmest day of the year is August 5, with an average hourly wind speed of 11.4 miles per hour.
Average Wind Speed
The predominant average hourly wind direction at Plymouth varies throughout the year.
The wind is most often from the east for 1.9 weeks, from April 21 to May 4, with a peak percentage of 28% on April 28. The wind is most often from the west for 12 months, from May 4 to April 21, with a peak percentage of 40% on January 1.
Plymouth 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 some seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.1 months, from July 3 to October 7, with an average temperature above 59°F. The day of the year with the warmest water is August 9, with an average temperature of 62°F.
The time of year with cooler water lasts for 3.9 months, from January 3 to May 1, with an average temperature below 51°F. The day of the year with the coolest water is March 6, with an average temperature of 48°F.
Average Water Temperature
Best Time of Year to Visit
To characterize how pleasant the weather is at Plymouth 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 Plymouth for general outdoor tourist activities is from late June to early September, with a peak score in the last week of July.
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 Plymouth for hot-weather activities is from mid July to early August, with a peak score in the last week of July.
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 at Plymouth typically lasts for 9.0 months (277 days), from around March 7 to around December 8, rarely starting before February 7 or after April 11, and rarely ending before November 13 or after January 5.
Time Spent in Various Temperature Bands and the Growing Season
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
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 at Plymouth should appear around May 8, only rarely appearing before April 21 or after May 26.
Growing Degree Days
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 4 to August 15, with an average daily incident shortwave energy per square meter above 5.4 kWh. The brightest day of the year is June 28, with an average of 6.6 kWh.
The darker period of the year lasts for 3.8 months, from October 25 to February 19, with an average daily incident shortwave energy per square meter below 1.9 kWh. The darkest day of the year is December 25, with an average of 0.7 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Plymouth are 50.350 deg latitude, -4.117 deg longitude, and 69 ft elevation.
The topography within 2 miles of Plymouth contains only modest variations in elevation, with a maximum elevation change of 407 feet and an average elevation above sea level of 110 feet. Within 10 miles contains only modest variations in elevation (1,670 feet). Within 50 miles contains very significant variations in elevation (2,133 feet).
The area within 2 miles of Plymouth is covered by artificial surfaces (34%), water (33%), cropland (16%), and grassland (12%), within 10 miles by water (42%) and cropland (22%), and within 50 miles by water (58%) and grassland (18%).
This report illustrates the typical weather at Plymouth, 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
Plymouth has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.
In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.
The stations on which we may fall back include but are not limited to Chivenor, Exeter Airport, Newquay Cornwall Airport, Culdrose, St Athan Royal Air Force Base, Cardiff Airport, Pembrey Sands, and Land's End Airport.
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.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.