There are days when operations are cancelled due to weather. However, if you look at the records, and we have, missions were flown even under the most apalling conditions; there were very few days when there was no aerial activity. The weather you see in OFF, every day, is based on met records, data from the 'Comic Cuts', TSTB, squadron and battalion war diaries, artillery records, and various other sources. Unfortunately, we can't tune it to specific locales, so one weather system must fit the entire Front, but the weather you see was what the troops saw on any given day.
Cheers,
shredward