Sometimes in March and April, the famous showers with wintry load may enter the Low Countries from the N to NW. The upper air is very cold: at 850 hPa usually less than -5°C and at 500 hPa usually less than -30°C. This may result in heavy showers with rain, sleet, snow, small hail and accompanied by a rumble of thunder. During precipitation, temperatures at 1,5 meter may drop just above freezing, and sometimes a cover of snow is formed. In between the showers, the sky is deep blue with very good visibilities. At that moment temperatures at 1,5 m may rise up to 10°C.  

The picture was taken on a very unstable Spring day. On the right side an incoming shower with snow pellets which gave a very dark appearance of the sky till the earth's surface.