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Average Weather in Douglas Isle of Man

In Douglas, the summers are cool and windy; the winters are long, very cold, wet, and extremely windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 38°F to 63°F and is rarely below 31°F or above 69°F.

Based on the tourism score, the best time of year to visit Douglas for warm-weather activities is from early July to early September.

Climate Summary

coldcoldcoolcoldJanFebMarAprMayJunJulAugSepOctNovDecNowNow52%52%34%34%overcastclearprecipitation: 3.6 inprecipitation: 3.6 in1.7 in1.7 inmuggy: 0%muggy: 0%drydrytourism score: 5.7tourism score: 5.70.00.0
Click on each chart for more information.

Temperature

The warm season lasts for 3.1 months, from June 15 to September 18, with an average daily high temperature above 60°F. The hottest day of the year is July 30, with an average high of 63°F and low of 55°F.

The cool season lasts for 4.1 months, from November 29 to April 2, with an average daily high temperature below 49°F. The coldest day of the year is February 18, with an average low of 38°F and high of 45°F.

Average High and Low Temperature

Average High and Low Temperature in DouglaswarmcoolcoolJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FFeb 1845°FFeb 1845°FJul 3063°FJul 3063°F38°F38°F55°F55°FJun 1560°FJun 1560°FSep 1860°FSep 1860°FNov 2949°FNov 2949°FApr 249°FApr 249°F50°F50°F52°F52°F42°F42°F41°F41°FNowNow
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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

Average Hourly Temperature in DouglasJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMNowNowvery coldcoldcoldcoolvery cold
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
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Metchosin, Canada (4,520 miles away) is the far-away foreign place with temperatures most similar to Douglas (view comparison).

Clouds

In Douglas, 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 Douglas begins around April 13 and lasts for 5.9 months, ending around October 10. On July 15, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 52% of the time, and overcast or mostly cloudy 48% of the time.

The cloudier part of the year begins around October 10 and lasts for 6.1 months, ending around April 13. On January 27, 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

Cloud Cover Categories in DouglasclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 1552%Jul 1552%Jan 2734%Jan 2734%Apr 1343%Apr 1343%Oct 1043%Oct 1043%NowNowclearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Douglas varies throughout the year.

The wetter season lasts 4.1 months, from October 6 to February 9, with a greater than 37% chance of a given day being a wet day. The chance of a wet day peaks at 48% on January 3.

The drier season lasts 7.9 months, from February 9 to October 6. The smallest chance of a wet day is 26% on July 13.

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 48% on January 3.

Daily Chance of Precipitation

Daily Chance of Precipitation in DouglaswetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jan 348%Jan 348%Jul 1326%Jul 1326%Jan 148%Jan 148%Oct 637%Oct 637%Feb 937%Feb 937%NowNowrain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

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. Douglas experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year in Douglas. The most rain falls during the 31 days centered around October 27, with an average total accumulation of 3.6 inches.

The least rain falls around May 6, with an average total accumulation of 1.7 inches.

Average Monthly Rainfall

Average Monthly Rainfall in DouglasJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in1 in1 in2 in2 in3 in3 in4 in4 in5 in5 in6 in6 in7 in7 inOct 273.6 inOct 273.6 inMay 61.7 inMay 61.7 inDec 253.6 inDec 253.6 inJun 221.9 inJun 221.9 inNowNow
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

The length of the day in Douglas varies extremely over the course of the year. In 2021, the shortest day is December 21, with 7 hours, 21 minutes of daylight; the longest day is June 21, with 17 hours, 11 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight in DouglasJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 2012 hr, 7 minMar 2017 hr, 11 minJun 2117 hr, 11 minJun 2112 hr, 12 minSep 2212 hr, 12 minSep 227 hr, 21 minDec 217 hr, 21 minDec 21nightnightdayNowNow
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 4:43 AM on June 18, and the latest sunrise is 3 hours, 54 minutes later at 8:37 AM on December 29. The earliest sunset is at 3:54 PM on December 13, and the latest sunset is 6 hours, 1 minute later at 9:55 PM on June 24.

Daylight saving time (DST) is observed in Douglas during 2021, starting in the spring on March 28, lasting 7.1 months, and ending in the fall on October 31.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in DouglasJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 184:43 AMJun 184:43 AM9:55 PMJun 249:55 PMJun 24Dec 133:54 PMDec 133:54 PM8:37 AMDec 298:37 AMDec 29Mar 28DSTMar 28DSTDSTOct 31DSTOct 31daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunsetNowNow
The solar day over the course of the year 2021. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Moon

The figure below presents a compact representation of key lunar data for 2021. 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

The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.

Humidity

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 Douglas, 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

Humidity Comfort Levels in DouglasJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Jul 30%Jul 30%NowNowcomfortablecomfortabledrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

Wind

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 Douglas experiences extreme seasonal variation over the course of the year.

The windier part of the year lasts for 5.7 months, from October 2 to March 24, with average wind speeds of more than 17.0 miles per hour. The windiest day of the year is January 3, with an average hourly wind speed of 21.6 miles per hour.

The calmer time of year lasts for 6.3 months, from March 24 to October 2. The calmest day of the year is June 14, with an average hourly wind speed of 12.3 miles per hour.

Average Wind Speed

Average Wind Speed in DouglaswindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph5 mph5 mph10 mph10 mph15 mph15 mph20 mph20 mph25 mph25 mph30 mph30 mphJan 321.6 mphJan 321.6 mphJun 1412.3 mphJun 1412.3 mphOct 217.0 mphOct 217.0 mphMar 2417.0 mphMar 2417.0 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

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

The wind is most often from the south for 2.0 months, from April 7 to June 6, with a peak percentage of 30% on May 29. The wind is most often from the west for 10 months, from June 6 to April 7, with a peak percentage of 40% on January 1.

Wind Direction

Wind Direction in DouglasWSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestsoutheastnorth
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Douglas 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 3.4 months, from July 6 to October 19, with an average temperature above 56°F. The day of the year with the warmest water is August 24, with an average temperature of 59°F.

The time of year with cooler water lasts for 3.7 months, from January 6 to April 27, with an average temperature below 48°F. The day of the year with the coolest water is March 4, with an average temperature of 45°F.

Average Water Temperature

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Best Time of Year to Visit

To characterize how pleasant the weather is in Douglas 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 Douglas for general outdoor tourist activities is from early July to early September, with a peak score in the last week of July.

Tourism Score

Tourism Score in Douglasbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810105.75.70.00.0NowNowprecipitationprecipitationcloudscloudstemperaturetemperature tourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

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 Douglas for hot-weather activities is for the entire month of July, with a peak score in the third week of July.

Beach/Pool Score

Beach/Pool Score in DouglasJanFebMarAprMayJunJulAugSepOctNovDec002244668810100.50.50.00.0NowNowprecipitationprecipitationcloudsclouds
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

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.

Growing Season

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 Douglas typically lasts for 8.5 months (258 days), from around March 20 to around December 3, rarely starting before February 5 or after April 24, and rarely ending before October 26 or after January 7.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Douglasgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Mar 2050%Mar 2050%Dec 350%Dec 390%Apr 2490%Apr 2490%Oct 2690%Oct 2610%Feb 510%Feb 510%Jan 710%Jan 7Jul 27100%Jul 27100%NowNowvery coldcoldcool
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
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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 Douglas should appear around May 29, only rarely appearing before May 17 or after June 17.

Growing Degree Days

Growing Degree Days in DouglasJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F200°F200°F400°F400°F600°F600°F800°F800°F1,000°F1,000°F1,200°F1,200°FMay 2990°FMay 2990°FSep 16900°FSep 16900°FDec 311,122°FDec 311,122°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

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 2 to August 11, with an average daily incident shortwave energy per square meter above 5.1 kWh. The brightest day of the year is June 22, with an average of 6.2 kWh.

The darker period of the year lasts for 4.0 months, from October 22 to February 23, with an average daily incident shortwave energy per square meter below 1.6 kWh. The darkest day of the year is December 22, with an average of 0.5 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in DouglasbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 226.2 kWhJun 226.2 kWhDec 220.5 kWhDec 220.5 kWhMay 25.1 kWhMay 25.1 kWhAug 115.1 kWhAug 115.1 kWhOct 221.6 kWhOct 221.6 kWhFeb 231.6 kWhFeb 231.6 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Douglas are 54.150 deg latitude, -4.483 deg longitude, and 102 ft elevation.

The topography within 2 miles of Douglas contains only modest variations in elevation, with a maximum elevation change of 482 feet and an average elevation above sea level of 122 feet. Within 10 miles contains only modest variations in elevation (2,028 feet). Within 50 miles also contains large variations in elevation (2,034 feet).

The area within 2 miles of Douglas is covered by water (44%), grassland (25%), trees (16%), and artificial surfaces (15%), within 10 miles by water (53%) and grassland (33%), and within 50 miles by water (91%).

Data Sources

This report illustrates the typical weather in Douglas, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Douglas.

For each station, the records are corrected for the elevation difference between that station and Douglas 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 Douglas is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Douglas and a given station.

The stations contributing to this reconstruction are: Isle Of Man / Ronaldsway Airport (90%, 12 kilometers, southwest); Barrow/Walney Island Airport (5%, 80 kilometers, east); and West Freugh (4.8%, 84 kilometers, north).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports 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.

Disclaimer

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.