I certainly don't mind the rain at all, I almost love it!
I did a short fell-race on Monday evening in the pouring rain; the 'Trunce', & was only 50 seconds off a PB!! (including 3 'wadings' of the River Don!)
One day last week I even ran to work in the 'beginings' of thunderstorm, which turned out to be hailstones descending, not rain
But......
In February I had considered entering a fell-race up in Wharfedale, but it snowed on the morning of the event!
We had 3 inches here in Wakefield, & doubtless more at the race HQ, the organisers were undecided whether to go ahead or not - YES - fell-runners thinking about cancelling on the grounds of safety (or simply tieing up the local rescue services by looking for us all)
I made the decision to drive up, on the off-chance' that it was still on.
Thankfully it was, & I must say that it was one of the best (most enjoyable) races I've done...................................... 5 miles (& 1260 feet of climbing) around Ilkley Moor in the mist & falling snow

http://www.ilkleyharriers.org.uk/index.php?page=imr
I got a reasonable result for a first attempt at the course (& thus not knowing where the steepest climbs/descents were), finishing in 119th/215 @ 1.00:16
I'm 5th in-line, in a 'hi-viz' hat & yellow jersey sleeves