I think you've just got to go for it regardless of the weather.
There was a show yesterday about 1/2 mile from me, ( I don't go as it's too close ) and it was abandoned just after 1pm

we had loads of heavy rain & thunderstorms during yesterday and into the night, it even came on the tv last night that there was some serious flooding around the Darlington area of Co; Durham....
The show I went to today I had to drive through Darlington

anyway, I went and drove up to Raby Castle through some quite heavy showers only to find I drove out of the rain

the display field was full of cars & m/cycles and although it was overcast we all walked round in T shirts as it was so warm, great show and it started to rain at 5pm as we were getting ready for the off .. it rained all the way home... at least all the mud was washed off the underside
Mal