Climate and Average Weather Year Round in Heerlen Netherlands
In Heerlen, 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 33°F to 74°F and is rarely below 20°F or above 85°F.
Based on the tourism score, the best time of year to visit Heerlen for warm-weather activities is from late June to early September.
Average Temperature in Heerlen
The warm season lasts for 3.1 months, from June 6 to September 9, with an average daily high temperature above 68°F. The hottest month of the year in Heerlen is July, with an average high of 73°F and low of 57°F.
The cool season lasts for 3.7 months, from November 18 to March 10, with an average daily high temperature below 48°F. The coldest month of the year in Heerlen is January, with an average low of 33°F and high of 42°F.
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.
Burnaby, Canada (4,896 miles away) is the far-away foreign place with temperatures most similar to Heerlen (view comparison).
In Heerlen, 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 Heerlen begins around March 23 and lasts for 6.7 months, ending around October 13.
The clearest month of the year in Heerlen is July, during which on average the sky is clear, mostly clear, or partly cloudy 56% of the time.
The cloudier part of the year begins around October 13 and lasts for 5.3 months, ending around March 23.
The cloudiest month of the year in Heerlen is December, during which on average the sky is overcast or mostly cloudy 72% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Heerlen varies throughout the year.
The wetter season lasts 8.3 months, from May 9 to January 19, with a greater than 30% chance of a given day being a wet day. The month with the most wet days in Heerlen is December, with an average of 10.5 days with at least 0.04 inches of precipitation.
The drier season lasts 3.7 months, from January 19 to May 9. The month with the fewest wet days in Heerlen is April, with an average of 7.8 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 Heerlen is June, with an average of 9.7 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 34% on June 12.
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. Heerlen experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year in Heerlen. The month with the most rain in Heerlen is June, with an average rainfall of 2.2 inches.
The month with the least rain in Heerlen is April, with an average rainfall of 1.5 inches.
The length of the day in Heerlen varies extremely over the course of the year. In 2023, the shortest day is December 22, with 7 hours, 56 minutes of daylight; the longest day is June 21, with 16 hours, 32 minutes of daylight.
The earliest sunrise is at 5:21 AM on June 17, and the latest sunrise is 3 hours, 17 minutes later at 8:38 AM on December 31. The earliest sunset is at 4:29 PM on December 12, and the latest sunset is 5 hours, 24 minutes later at 9:54 PM on June 26.
Daylight saving time (DST) is observed in Heerlen during 2023, starting in the spring on March 26, lasting 7.1 months, and ending in the fall on October 29.
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.
The figure below presents a compact representation of key lunar data for 2023. 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.
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 Heerlen, 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.
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 Heerlen experiences significant seasonal variation over the course of the year.
The windier part of the year lasts for 5.6 months, from October 16 to April 2, with average wind speeds of more than 10.7 miles per hour. The windiest month of the year in Heerlen is January, with an average hourly wind speed of 12.8 miles per hour.
The calmer time of year lasts for 6.4 months, from April 2 to October 16. The calmest month of the year in Heerlen is August, with an average hourly wind speed of 8.7 miles per hour.
The predominant average hourly wind direction in Heerlen varies throughout the year.
The wind is most often from the west for 8.3 months, from January 22 to October 1, with a peak percentage of 48% on July 7. The wind is most often from the south for 3.7 months, from October 1 to January 22, with a peak percentage of 42% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Heerlen 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 Heerlen for general outdoor tourist activities is from late June to early September, with a peak score in the first week of August.
Tourism Score in Heerlen
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 Heerlen 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 Heerlen
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).
The growing season in Heerlen typically lasts for 7.0 months (213 days), from around April 12 to around November 10, rarely starting before March 23 or after April 30, and rarely ending before October 16 or after December 5.
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 Heerlen should appear around April 19, only rarely appearing before April 4 or after May 4.
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 month of the year in Heerlen is June, with an average of 6.3 kWh.
The darker period of the year lasts for 3.7 months, from October 28 to February 17, with an average daily incident shortwave energy per square meter below 1.8 kWh. The darkest month of the year in Heerlen is December, with an average of 0.7 kWh.
For the purposes of this report, the geographical coordinates of Heerlen are 50.884 deg latitude, 5.982 deg longitude, and 374 ft elevation.
The topography within 2 miles of Heerlen contains only modest variations in elevation, with a maximum elevation change of 374 feet and an average elevation above sea level of 403 feet. Within 10 miles contains only modest variations in elevation (1,043 feet). Within 50 miles contains very significant variations in elevation (3,058 feet).
The area within 2 miles of Heerlen is covered by artificial surfaces (67%) and cropland (26%), within 10 miles by cropland (53%) and artificial surfaces (29%), and within 50 miles by cropland (43%) and trees (23%).
This report illustrates the typical weather in Heerlen, 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 Heerlen.
For each station, the records are corrected for the elevation difference between that station and Heerlen 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 Heerlen is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Heerlen and a given station.
The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Heerlen and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 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 © OpenStreetMap contributors.
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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