With an average temperature in De Bilt of 19.0°C compared to the climatological average of 18.3°C, July was a warm month. Except for a few hot days, the month had a fairly moderate temperature trend with average afternoon temperatures and mild nights. The month of July had many regional differences when looking at precipitation extremes, precipitation deficits, and sunshine hours.
Extreme Heat and Thunderstorms
The month of July started with extreme heat. Our country was in very warm tropical air, causing it to be tropical warm (30°C or more) everywhere on July 1, and the temperature in the southeastern half rose well above 35°C. In addition to a yellow code for the heat plan (for persistent heat), the KNMI also issued an orange code for extreme heat in the southeastern part of the country. On July 2, less warm air flowed into our country at the end of the day, accompanied by severe thunderstorms, for which we also issued an orange code for thunderstorms in eastern provinces.
Changeable Summer Weather
The rest of the month consisted of changeable summer weather, where we fluctuated between temperatures of 19°C and 25°C. Inland, we had many showers, especially in the second half of the month. The national differences in the weather picture were significant, with quite a bit of cloud cover and daily heavy showers in the east, locally also with thunderstorms and a lot of precipitation. In the west, there was more room for the sun, and dry periods predominated.
Almost the Maximum Number of Warm Days
In De Bilt, there were 28 warm days (20°C or more) this month, which is about five more than normal. The number of warm days varied from about 25 in the Wadden area to 30 in the southeast, just one day short of the maximum possible number. The counts of 9 summer days and 2 tropical days exactly matched the climatological average. In De Bilt, there was also one extremely warm day (at least 35°C), while there were two in the southeast.
Significant Difference in Precipitation
With a national average of 72 millimeters of precipitation, compared to a climatological average of 78 millimeters, July was slightly on the dry side. Just like in June, the differences were large: in the northeast it was wet, with locally 120 to 150 millimeters of precipitation. However, in the northwest and southwest and southeast, July was again a dry month, with many places receiving between 20 and 60 millimeters of precipitation.
Precipitation Deficit Remains Large in the Southwest
Due to the wetter character, the precipitation deficit stabilized on average across the country around a value of 200 millimeters, which corresponds to the 5% driest years. In the southwest, the precipitation deficit further increased to about 300 millimeters, while in the extreme northeast, the precipitation deficit at the end of July was still less than 100 millimeters.
Sunny at the Coast, Gloomy in the East
The amount of sunshine in July hardly deviated from the climatological average, with an average of 225 hours of sunshine across the country compared to 220 hours normally. It was sunniest on the west coast, at the KNMI station Hoek van Holland with 262 sunshine hours. In the east, the sun shone less often, with only 170 sunshine hours in Nieuw-Beerta.