Summer Weather in Aland Islands Åland IslandsDaily high temperatures are around 64°F, rarely falling below 50°F or exceeding 76°F. The highest daily average high temperature is 68°F on July 24. Daily low temperatures increase by 5°F, from 44°F to 49°F, rarely falling below 36°F or exceeding 61°F. The highest daily average low temperature is 54°F on July 24. For reference, on July 24, the hottest day of the year, temperatures in Aland Islands typically range from 54°F to 68°F, while on February 10, the coldest day of the year, they range from 21°F to 31°F. The figure below shows you a compact characterization of the hourly average summer temperatures. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day. CloudsThe summer in Aland Islands experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 45% throughout the season. The lowest chance of overcast or mostly cloudy conditions is 41% on July 10. The clearest day of the summer is July 10, with clear, mostly clear, or partly cloudy conditions 59% of the time. For reference, on January 26, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 71%, while on July 10, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 59%. PrecipitationA wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Aland Islands, the chance of a wet day over the course of the summer is rapidly increasing, starting the season at 20% and ending it at 26%. For reference, the year's highest daily chance of a wet day is 31% on November 28, and its lowest chance is 16% on March 27. RainfallTo show variation within the season and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day. The average sliding 31-day rainfall during the summer in Aland Islands is gradually increasing, starting the season at 1.5 inches, when it rarely exceeds 2.7 inches or falls below 0.5 inches, and ending the season at 2.0 inches, when it rarely exceeds 3.3 inches or falls below 0.7 inches. The highest average 31-day accumulation is 2.0 inches on August 7. SunOver the course of the summer in Aland Islands, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 4 hours, 11 minutes, implying an average daily decrease of 2 minutes, 46 seconds, and weekly decrease of 19 minutes, 20 seconds. The shortest day of the summer is August 31, with 14 hours, 13 minutes of daylight and the longest day is June 21, with 18 hours, 58 minutes of daylight. The earliest sunrise of the summer in Aland Islands is 4:12 AM on June 19 and the latest sunrise is 2 hours, 20 minutes later at 6:32 AM on August 31. The latest sunset is 11:10 PM on June 22 and the earliest sunset is 2 hours, 25 minutes earlier at 8:46 PM on August 31. Daylight saving time is observed in Aland Islands during 2024, but it neither starts nor ends during the summer, so the entire season is in standard time. For reference, on June 20, the longest day of the year, the Sun rises at 4:12 AM and sets 18 hours, 58 minutes later, at 11:10 PM, while on December 21, the shortest day of the year, it rises at 9:44 AM and sets 5 hours, 47 minutes later, at 3:31 PM. 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. MoonThe figure below presents a compact representation of key lunar data for the summer of 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon. HumidityWe 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 chance that a given day will be muggy in Aland Islands is essentially constant during the summer, remaining within 1% of 1% throughout. The highest chance of a muggy day during the summer is 2% on July 29. For reference, on July 29, the muggiest day of the year, there are muggy conditions 2% of the time, while on September 16, the least muggy day of the year, there are muggy conditions 0% of the time. WindThis 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 Aland Islands is rapidly increasing during the summer, increasing from 11.4 miles per hour to 13.7 miles per hour over the course of the season. For reference, on December 14, the windiest day of the year, the daily average wind speed is 17.6 miles per hour, while on July 8, the calmest day of the year, the daily average wind speed is 11.3 miles per hour. The lowest daily average wind speed during the summer is 11.3 miles per hour on July 8. The hourly average wind direction in Aland Islands throughout the summer is predominantly from the south, with a peak proportion of 41% on July 23. Water TemperatureAland Islands 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 surface water temperature in Aland Islands is very rapidly increasing during the summer, rising by 12°F, from 47°F to 59°F, over the course of the season. The highest average surface water temperature during the summer is 62°F on August 7. Growing SeasonDefinitions 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 Aland Islands typically lasts for 4.5 months (138 days), from around May 16 to around October 1, rarely starting before April 28 or after June 3, and rarely ending before September 13 or after October 19. The summer in Aland Islands is more likely than not fully within the growing season, with the chance that a given day is in the growing season reaching a high of 100% on July 25. 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. The average accumulated growing degree days in Aland Islands are rapidly increasing during the summer, increasing by 863°F, from 86°F to 949°F, over the course of the season. Solar EnergyThis 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 in Aland Islands is very rapidly decreasing during the summer, falling by 2.4 kWh, from 6.3 kWh to 3.9 kWh, over the course of the season. The highest average daily incident shortwave solar energy during the summer is 6.6 kWh on June 29. TopographyFor the purposes of this report, the geographical coordinates of Aland Islands are 60.250 deg latitude, 20.000 deg longitude, and 0 ft elevation. The topography within 2 miles of Aland Islands 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 Aland Islands is covered by trees (59%), cropland (16%), and water (15%), within 10 miles by trees (54%) and water (27%), and within 50 miles by water (89%). Data SourcesThis report illustrates the typical weather in Aland Islands, 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 Mariehamn Airport page. DisclaimerThe 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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