Carry on regardless of weather.
At the the end of the day what's the difference between cleaning the windows on a sunny day then it's wind and rain the next, to actually cleaning in the wind and rain. Those windows you cleaned the day before will still be battered by the weather.
In the UK your always going to get wind and rain probably at least once a week so you may as well just get on with it.
As someone else mentioned the only time I call it a day is when I'm soaked down to my undies even with waterproofs on, then it just becomes uncomfortable to carry on.
Good news is by Wednesday this week high pressure is building in, could be 27c down here in south East by the end of the week!