Climate and Average Weather Year Round in Guernsey Guernsey
In Guernsey, the summers are comfortable and windy; the winters are long, cold, wet, and extremely windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 42°F to 68°F and is rarely below 35°F or above 74°F.
Based on the tourism score, the best time of year to visit Guernsey for warm-weather activities is from late June to mid September.
Climate in Guernsey
The warm season lasts for 3.0 months, from June 20 to September 21, with an average daily high temperature above 64°F. The hottest month of the year in Guernsey is August, with an average high of 67°F and low of 59°F.
The cool season lasts for 4.1 months, from November 29 to March 31, with an average daily high temperature below 52°F. The coldest month of the year in Guernsey is February, with an average low of 42°F and high of 48°F.
Average High and Low Temperature in Guernsey
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 Guernsey
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
In Guernsey, 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 in Guernsey begins around March 31 and lasts for 6.4 months, ending around October 12.
The clearest month of the year in Guernsey is July, during which on average the sky is clear, mostly clear, or partly cloudy 57% of the time.
The cloudier part of the year begins around October 12 and lasts for 5.6 months, ending around March 31.
The cloudiest month of the year in Guernsey is January, during which on average the sky is overcast or mostly cloudy 65% of the time.
Cloud Cover Categories in Guernsey
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 in Guernsey varies throughout the year.
The wetter season lasts 5.5 months, from September 27 to March 13, with a greater than 28% chance of a given day being a wet day. The month with the most wet days in Guernsey is December, with an average of 12.3 days with at least 0.04 inches of precipitation.
The drier season lasts 6.5 months, from March 13 to September 27. The month with the fewest wet days in Guernsey is July, with an average of 5.3 days with at least 0.04 inches of precipitation.
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 Guernsey is December, with an average of 12.3 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 40% on December 6.
Daily Chance of Precipitation in Guernsey
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. Guernsey experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Guernsey. The month with the most rain in Guernsey is December, with an average rainfall of 3.1 inches.
The month with the least rain in Guernsey is July, with an average rainfall of 1.1 inches.
Average Monthly Rainfall in Guernsey
The length of the day in Guernsey varies extremely over the course of the year. In 2022, the shortest day is December 21, with 8 hours, 9 minutes of daylight; the longest day is June 21, with 16 hours, 17 minutes of daylight.
Hours of Daylight and Twilight in Guernsey
The earliest sunrise is at 5:03 AM on June 17, and the latest sunrise is 3 hours, 3 minutes later at 8:06 AM on December 31. The earliest sunset is at 4:10 PM on December 12, and the latest sunset is 5 hours, 10 minutes later at 9:20 PM on June 25.
Daylight saving time (DST) is observed in Guernsey during 2022, starting in the spring on March 27, lasting 7.1 months, and ending in the fall on October 30.
Sunrise & Sunset with Twilight and Daylight Saving Time in Guernsey
The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.
Solar Elevation and Azimuth in Guernsey
The figure below presents a compact representation of key lunar data for 2022. 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.
Moon Rise, Set & Phases in Guernsey
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 in Guernsey, 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 in Guernsey
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 in Guernsey experiences extreme seasonal variation over the course of the year.
The windier part of the year lasts for 5.7 months, from October 6 to March 30, with average wind speeds of more than 16.2 miles per hour. The windiest month of the year in Guernsey is December, with an average hourly wind speed of 20.3 miles per hour.
The calmer time of year lasts for 6.3 months, from March 30 to October 6. The calmest month of the year in Guernsey is July, with an average hourly wind speed of 12.2 miles per hour.
Average Wind Speed in Guernsey
The predominant average hourly wind direction in Guernsey is from the west throughout the year.
Wind Direction in Guernsey
Guernsey 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 3.3 months, from July 13 to October 23, with an average temperature above 59°F. The month of the year in Guernsey with the warmest water is August, with an average temperature of 62°F.
The time of year with cooler water lasts for 3.9 months, from January 8 to May 4, with an average temperature below 51°F. The month of the year in Guernsey with the coolest water is March, with an average temperature of 48°F.
Average Water Temperature in Guernsey
To characterize how pleasant the weather is in Guernsey 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 Guernsey for general outdoor tourist activities is from late June to mid September, with a peak score in the last week of July.
Tourism Score in Guernsey
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 Guernsey for hot-weather activities is from mid July to mid August, with a peak score in the first week of August.
Beach/Pool Score in Guernsey
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).
While it does not do so every year, freezing temperatures are seen in Guernsey over some winters. The day least likely to be in the growing season is January 16, with a 58% chance.
Time Spent in Various Temperature Bands and the Growing Season in Guernsey
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 in Guernsey should appear around May 3, only rarely appearing before April 15 or after May 23.
Growing Degree Days in Guernsey
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 6 to August 16, with an average daily incident shortwave energy per square meter above 5.6 kWh. The brightest month of the year in Guernsey is June, with an average of 6.7 kWh.
The darker period of the year lasts for 3.8 months, from October 26 to February 20, with an average daily incident shortwave energy per square meter below 2.0 kWh. The darkest month of the year in Guernsey is December, with an average of 0.8 kWh.
Average Daily Incident Shortwave Solar Energy in Guernsey
For the purposes of this report, the geographical coordinates of Guernsey are 49.455 deg latitude, -2.576 deg longitude, and 0 ft elevation.
The topography within 2 miles of Guernsey 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 Guernsey is covered by trees (40%) and grassland (30%), within 10 miles by water (95%), and within 50 miles by water (93%).
This report illustrates the typical weather in Guernsey, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
The details of the data sources used for this report can be found on the Guernsey Airport page.
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.
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