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Average Weather at Mariehamn Airport Åland Islands

At Mariehamn Airport, the summers are short, comfortable, and partly cloudy; the winters are long, freezing, dry, and mostly cloudy; and it is windy year round. Over the course of the year, the temperature typically varies from 21°F to 68°F and is rarely below 3°F or above 76°F.

Based on the tourism score, the best time of year to visit Mariehamn Airport for warm-weather activities is from early July to mid August.

Climate Summary

freezingvery coldcoldcoolcomfortablecoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDecNowNow59%59%29%29%overcastclearprecipitation: 2.0 inprecipitation: 2.0 in0.8 in0.8 inmuggy: 2%muggy: 2%0%0%drydrytourism score: 6.7tourism score: 6.70.00.0
Click on each chart for more information.

Temperature

The warm season lasts for 2.8 months, from June 11 to September 6, with an average daily high temperature above 61°F. The hottest day of the year is July 25, with an average high of 68°F and low of 54°F.

The cold season lasts for 4.0 months, from November 27 to March 27, with an average daily high temperature below 38°F. The coldest day of the year is February 10, with an average low of 21°F and high of 31°F.

Average High and Low Temperature

Average High and Low Temperature at Mariehamn AirportwarmcoldcoldJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F10°F10°F20°F20°F30°F30°F40°F40°F50°F50°F60°F60°F70°F70°F80°F80°F90°F90°F100°F100°FFeb 1031°FFeb 1031°FJul 2568°FJul 2568°F21°F21°F54°F54°FJun 1161°FJun 1161°FSep 661°FSep 661°FNov 2738°FNov 2738°FMar 2738°FMar 2738°F46°F46°F48°F48°F31°F31°F26°F26°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 at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec12 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMNowNowfreezingvery coldvery coldcoldcoldcoolcomfortablefreezing
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.

Seward, Alaska, United States (4,115 miles away); Haines, Alaska, United States (4,088 miles); and Channel-Port aux Basques, Canada (3,130 miles) are the far-away foreign places with temperatures most similar to Mariehamn Airport (view comparison).

Clouds

At Mariehamn Airport, 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 Mariehamn Airport begins around April 29 and lasts for 5.4 months, ending around October 10. On July 11, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 59% of the time, and overcast or mostly cloudy 41% of the time.

The cloudier part of the year begins around October 10 and lasts for 6.6 months, ending around April 29. On January 26, the cloudiest day of the year, the sky is overcast or mostly cloudy 71% of the time, and clear, mostly clear, or partly cloudy 29% of the time.

Cloud Cover Categories

Cloud Cover Categories at Mariehamn AirportclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 1159%Jul 1159%Jan 2629%Jan 2629%Apr 2944%Apr 2944%Oct 1044%Oct 1044%NowNowclearmostly clearovercastpartly cloudy
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 at Mariehamn Airport varies throughout the year.

The wetter season lasts 5.5 months, from July 30 to January 13, with a greater than 24% chance of a given day being a wet day. The chance of a wet day peaks at 31% on November 29.

The drier season lasts 6.5 months, from January 13 to July 30. The smallest chance of a wet day is 16% on March 28.

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 29% on October 18.

Daily Chance of Precipitation

Daily Chance of Precipitation at Mariehamn AirportwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Nov 2931%Nov 2931%Mar 2816%Mar 2816%Jul 3024%Jul 3024%Jan 1324%Jan 1324%NowNowrainsnowmixed
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. Mariehamn Airport experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year at Mariehamn Airport. The most rain falls during the 31 days centered around August 8, with an average total accumulation of 2.0 inches.

The least rain falls around March 1, with an average total accumulation of 0.5 inches.

Average Monthly Rainfall

Average Monthly Rainfall at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec0 in0 in1 in1 in2 in2 in3 in3 in4 in4 inAug 82.0 inAug 82.0 inMar 10.5 inMar 10.5 inOct 301.9 inOct 301.9 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.

Snowfall

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. Mariehamn Airport experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 5.2 months, from November 6 to April 13, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around January 22, with an average total liquid-equivalent accumulation of 0.4 inches.

The snowless period of the year lasts for 6.8 months, from April 13 to November 6. The least snow falls around July 29, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall at Mariehamn AirportsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.0 in0.5 in0.5 in1.0 in1.0 in1.5 in1.5 in2.0 in2.0 inJan 220.4 inJan 220.4 inJul 290.0 inJul 290.0 inNov 60.1 inNov 60.1 inApr 130.1 inApr 130.1 in
The average liquid-equivalent snowfall (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 rainfall.

Sun

The length of the day at Mariehamn Airport varies extremely over the course of the year. In 2021, the shortest day is December 21, with 5 hours, 50 minutes of daylight; the longest day is June 21, with 18 hours, 55 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 8 minMar 2012 hr, 8 minMar 2018 hr, 55 minJun 2118 hr, 55 minJun 2112 hr, 15 minSep 2212 hr, 15 minSep 225 hr, 50 minDec 215 hr, 50 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 4:14 AM on June 19, and the latest sunrise is 5 hours, 31 minutes later at 9:45 AM on December 27. The earliest sunset is at 3:32 PM on December 16, and the latest sunset is 7 hours, 38 minutes later at 11:09 PM on June 23.

Daylight saving time (DST) is observed at Mariehamn Airport 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 at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 194:14 AMJun 194:14 AM11:09 PMJun 2311:09 PMJun 23Dec 163:32 PMDec 163:32 PM9:45 AMDec 279:45 AMDec 27Mar 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 at Mariehamn Airport, 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, staying within 1% of 1% throughout.

Humidity Comfort Levels

Humidity Comfort Levels at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec0%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%Nov 90%Nov 90%Jul 302%Jul 302%comfortablecomfortabledrydryhumidhumid
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 at Mariehamn Airport experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.0 months, from September 17 to March 15, with average wind speeds of more than 14.5 miles per hour. The windiest day of the year is December 15, with an average hourly wind speed of 17.6 miles per hour.

The calmer time of year lasts for 6.0 months, from March 15 to September 17. The calmest day of the year is July 9, with an average hourly wind speed of 11.3 miles per hour.

Average Wind Speed

Average Wind Speed at Mariehamn AirportwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph0 mph5 mph5 mph10 mph10 mph15 mph15 mph20 mph20 mph25 mph25 mphDec 1517.6 mphDec 1517.6 mphJul 911.3 mphJul 911.3 mphSep 1714.5 mphSep 1714.5 mphMar 1514.5 mphMar 1514.5 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 at Mariehamn Airport varies throughout the year.

The wind is most often from the south for 7.8 months, from February 25 to October 18, with a peak percentage of 41% on July 24. The wind is most often from the west for 4.2 months, from October 18 to February 25, with a peak percentage of 40% on January 1.

Wind Direction

Wind Direction at Mariehamn AirportWSWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestsouthnortheast
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

Mariehamn Airport 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 2.4 months, from July 2 to September 15, with an average temperature above 56°F. The day of the year with the warmest water is August 5, with an average temperature of 62°F.

The time of year with cooler water lasts for 4.6 months, from December 16 to May 5, with an average temperature below 39°F. The day of the year with the coolest water is March 5, with an average temperature of 33°F.

Average Water Temperature

Average Water Temperature at Mariehamn AirportwarmcoolJanFebMarAprMayJunJulAugSepOctNovDec25°F25°F30°F30°F35°F35°F40°F40°F45°F45°F50°F50°F55°F55°F60°F60°F65°F65°F70°F70°FAug 562°FAug 562°F33°FMar 533°FMar 5Jul 256°FJul 256°FSep 1556°FSep 1556°FDec 1639°FDec 1639°FMay 539°FMay 539°FNowNow
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 at Mariehamn Airport 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 Mariehamn Airport for general outdoor tourist activities is from early July to mid August, with a peak score in the third week of July.

Tourism Score

Tourism Score at Mariehamn Airportbest timeJanFebMarAprMayJunJulAugSepOctNovDec002244668810106.76.70.00.0NowNowprecipitationprecipitationcloudscloudstemperaturetemperature 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 Mariehamn Airport for hot-weather activities is from mid July to early August, with a peak score in the last week of July.

Beach/Pool Score

Beach/Pool Score at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec002244668810102.12.10.00.0NowNowprecipitationprecipitationcloudscloudstemperaturetemperature
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 at Mariehamn Airport typically lasts for 4.5 months (138 days), from around May 17 to around October 2, rarely starting before April 29 or after June 4, and rarely ending before September 14 or after October 20.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season at Mariehamn Airportgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%May 1750%May 1750%Oct 250%Oct 250%Jun 490%Jun 490%Sep 1490%Sep 1490%Apr 2910%Apr 2910%Oct 2010%Oct 2010%0%Dec 70%Dec 7Jul 26100%Jul 26100%NowNowfrigidfreezingvery coldcoldcoolcomfortable
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 at Mariehamn Airport should appear around June 3, only rarely appearing before May 23 or after June 17.

Growing Degree Days

Growing Degree Days at Mariehamn AirportJanFebMarAprMayJunJulAugSepOctNovDec0°F0°F200°F200°F400°F400°F600°F600°F800°F800°F1,000°F1,000°F1,200°F1,200°FJun 390°FJun 390°FAug 26900°FAug 26900°FDec 311,104°FDec 311,104°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 3.0 months, from May 8 to August 8, with an average daily incident shortwave energy per square meter above 5.3 kWh. The brightest day of the year is June 27, with an average of 6.6 kWh.

The darker period of the year lasts for 4.4 months, from October 15 to February 27, with an average daily incident shortwave energy per square meter below 1.4 kWh. The darkest day of the year is December 21, with an average of 0.2 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy at Mariehamn AirportbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJun 276.6 kWhJun 276.6 kWhDec 210.2 kWhDec 210.2 kWhMay 85.3 kWhMay 85.3 kWhAug 85.3 kWhAug 85.3 kWhOct 151.4 kWhOct 151.4 kWhFeb 271.4 kWhFeb 271.4 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 Mariehamn Airport are 60.122 deg latitude, 19.898 deg longitude, and 20 ft elevation.

The topography within 2 miles of Mariehamn Airport contains only modest variations in elevation, with a maximum elevation change of 223 feet and an average elevation above sea level of 60 feet. Within 10 miles also contains only modest variations in elevation (272 feet). Within 50 miles also contains only modest variations in elevation (453 feet).

The area within 2 miles of Mariehamn Airport is covered by trees (52%), artificial surfaces (19%), and cropland (18%), within 10 miles by water (50%) and trees (37%), and within 50 miles by water (86%) and trees (10%).

Data Sources

This report illustrates the typical weather at Mariehamn Airport, 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

Mariehamn Airport 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 are Stockholm Arlanda Airport, Stockholm-Bromma Airport, Tullinge, Uppsala, Pori Airport, Turku Airport, Gavle-Sandviken Airport, and Söderhamn Airport.

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.