Saw an unexpected spike this night

Normally my measurements are around 15 CPM. My running average is always around that number as well. But last night between 01:30 and 03:30 CET I saw a spike in the running average up to 22 CPM. That doesn’t seem like much, but my station is very stable throughout the year, so it stood out to me. I believe I also noticed an increase during the night at other stations in the Netherlands. According to the Windy app, at that time the wind was coming from the south (via France and Belgium).Has anybody else seen anything similar this night