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Average Weather in Iserlohn Germany

In Iserlohn, the summers are comfortable and partly cloudy and the winters are long, very cold, windy, and mostly cloudy. Over the course of the year, the temperature typically varies from 30°F to 72°F and is rarely below 17°F or above 84°F.

Climate Summary

very coldcoldcoolcomfortablecoolcoldvery coldJanFebMarAprMayJunJulAugSepOctNovDec56%56%25%25%overcastclearprecipitation: 2.7 inprecipitation: 2.7 in1.7 in1.7 inmuggy: 1%muggy: 1%0%0%drydrytourism score: 6.5tourism score: 6.50.00.0
Click on each chart for more information.

Based on the tourism score, the best time of year to visit Iserlohn for warm-weather activities is from late June to late August.

Temperature

The warm season lasts for 3.0 months, from June 7 to September 9, with an average daily high temperature above 65°F. The hottest day of the year is August 5, with an average high of 72°F and low of 56°F.

The cold season lasts for 3.8 months, from November 18 to March 10, with an average daily high temperature below 45°F. The coldest day of the year is February 8, with an average low of 30°F and high of 39°F.

Average High and Low Temperature

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 IserlohnJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMvery coldvery coldcoldcoldcoolcomfortable
The average hourly temperature, color coded into bands: 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 shaded overlays indicate night and civil twilight.

Anmore, Canada (4,901 miles away) is the far-away foreign place with temperatures most similar to Iserlohn (view comparison).

Clouds

In Iserlohn, 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 Iserlohn begins around March 27 and lasts for 6.5 months, ending around October 11. On July 22, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 56% of the time, and overcast or mostly cloudy 44% of the time.

The cloudier part of the year begins around October 11 and lasts for 5.5 months, ending around March 27. On December 26, the cloudiest day of the year, the sky is overcast or mostly cloudy 75% of the time, and clear, mostly clear, or partly cloudy 25% of the time.

Cloud Cover Categories

Cloud Cover Categories in IserlohnclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 2256%Jul 2256%Dec 2625%Dec 2625%Mar 2740%Mar 2740%Oct 1141%Oct 1141%clearmostly clearpartly cloudymostly cloudyovercast
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

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

The wetter season lasts 8.3 months, from May 24 to February 4, with a greater than 33% chance of a given day being a wet day. The chance of a wet day peaks at 39% on December 26.

The drier season lasts 3.6 months, from February 4 to May 24. The smallest chance of a wet day is 26% on March 4.

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 36% on July 12.

Daily Chance of Precipitation

Daily Chance of Precipitation in IserlohnwetwetdryJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Dec 2639%Dec 2639%Mar 426%Mar 426%May 2433%May 2433%Feb 433%Feb 433%rainmixed
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. Iserlohn experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year in Iserlohn. The most rain falls during the 31 days centered around December 27, with an average total accumulation of 2.5 inches.

The least rain falls around April 20, with an average total accumulation of 1.7 inches.

Average Monthly Rainfall

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

The sliding 31-day liquid-equivalent quantity of snowfall in Iserlohn does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in IserlohnsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.5 in1.0 in1.5 in2.0 in2.5 inJan 10.1 inJan 10.1 inJul 150.0 inJul 150.0 inJan 10.1 inJan 10.1 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 in Iserlohn varies extremely over the course of the year. In 2017, the shortest day is December 21, with 7 hours, 51 minutes of daylight; the longest day is June 21, with 16 hours, 37 minutes of daylight.

Hours of Daylight and Twilight

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 5:12 AM on June 15, and the latest sunrise is 3 hours, 22 minutes later at 8:34 AM on December 30. The earliest sunset is at 4:20 PM on December 12, and the latest sunset is 5 hours, 29 minutes later at 9:49 PM on June 25.

Daylight saving time (DST) is observed in Iserlohn during 2017, starting in the spring on March 26, lasting 7.1 months, and ending in the fall on October 29.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in IserlohnJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 155:12 AMJun 155:12 AM9:49 PMJun 259:49 PMJun 25Dec 124:20 PMDec 124:20 PM8:34 AMDec 308:34 AMDec 30Mar 26DSTMar 26DSTDSTOct 29DSTOct 29daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2017. 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.

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 Iserlohn, 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 IserlohnJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jan 240%Jan 240%Jul 131%Jul 131%comfortablecomfortabledrydryhumidhumid
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

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 Iserlohn experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 5.5 months, from October 17 to April 1, with average wind speeds of more than 10.7 miles per hour. The windiest day of the year is January 17, with an average hourly wind speed of 12.9 miles per hour.

The calmer time of year lasts for 6.5 months, from April 1 to October 17. The calmest day of the year is August 5, with an average hourly wind speed of 8.4 miles per hour.

Average Wind Speed

Average Wind Speed in IserlohnwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mph16 mph18 mph20 mphJan 1712.9 mphJan 1712.9 mphAug 58.4 mphAug 58.4 mphOct 1710.7 mphOct 1710.7 mphApr 110.7 mphApr 110.7 mph
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 Iserlohn varies throughout the year.

The wind is most often from the west for 8.1 months, from January 27 to September 30, with a peak percentage of 47% on July 8. The wind is most often from the south for 3.9 months, from September 30 to January 27, with a peak percentage of 43% on January 1.

Wind Direction

Wind Direction in IserlohnSWSJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsoutheastnorth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Best Time of Year to Visit

To characterize how pleasant the weather is in Iserlohn 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 Iserlohn for general outdoor tourist activities is from late June to late August, with a peak score in the first week of August.

Tourism Score

Tourism Score in Iserlohnbest timeJanFebMarAprMayJunJulAugSepOctNovDec02468106.56.50.00.0precipitationprecipitationcloudscloudstemperaturetemperaturetourism 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 Iserlohn for hot-weather activities is from mid July to mid August, with a peak score in the first week of August.

Beach/Pool Score

Beach/Pool Score in IserlohnJanFebMarAprMayJunJulAugSepOctNovDec02468103.23.20.00.0 precipitationprecipitationcloudscloudstemperaturetemperature
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 Iserlohn typically lasts for 6.6 months (203 days), from around April 16 to around November 4, rarely starting before March 28 or after May 3, and rarely ending before October 12 or after December 1.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in Iserlohngrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%50%Apr 1650%Apr 1650%Nov 450%Nov 490%May 390%May 390%Oct 1290%Oct 1210%Mar 2810%Mar 2810%Dec 110%Dec 10%Feb 10%Feb 1Jul 25100%Jul 25100%freezingvery coldcoldcoolcomfortablewarm
The percentage of time spent in various temperature bands: 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 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 Iserlohn should appear around April 28, only rarely appearing before April 14 or after May 13.

Growing Degree Days

Growing Degree Days in IserlohnJanFebMarAprMayJunJulAugSepOctNovDec0°F200°F400°F600°F800°F1,000°F1,200°F1,400°F1,600°F1,800°FApr 2890°FApr 2890°FJul 24900°FJul 24900°FDec 311,760°FDec 311,760°F
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 3.6 months, from April 30 to August 18, with an average daily incident shortwave energy per square meter above 5.2 kWh. The brightest day of the year is June 23, with an average of 6.3 kWh.

The darker period of the year lasts for 3.7 months, from October 26 to February 18, with an average daily incident shortwave energy per square meter below 1.7 kWh. The darkest day of the year is December 23, with an average of 0.6 kWh.

Average Daily Incident Shortwave Solar Energy

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 Iserlohn are 51.375 deg latitude, 7.703 deg longitude, and 853 ft elevation.

The topography within 2 miles of Iserlohn contains very significant variations in elevation, with a maximum elevation change of 981 feet and an average elevation above sea level of 929 feet. Within 10 miles also contains very significant variations in elevation (1,660 feet). Within 50 miles contains very significant variations in elevation (2,831 feet).

The area within 2 miles of Iserlohn is covered by trees (44%), artificial surfaces (43%), and grassland (10%), within 10 miles by trees (40%) and cropland (30%), and within 50 miles by cropland (39%) and trees (30%).

Data Sources

This report illustrates the typical weather in Iserlohn, 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Iserlohn.

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

The stations contributing to this reconstruction are: Dortmund Airport (66%, 17 kilometers, north); Düsseldorf International Airport (11%, 66 kilometers, west); Paderborn Lippstadt Airport (12%, 69 kilometers, northeast); and Cologne Bonn Airport (11%, 69 kilometers, southwest).

Other Data

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.

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.