Hi, I've raced in bad conditions, even in rain and mud during the night in a 24h race. I use disc brakes: they are not influenced by weather. If the race is not too long, you shouldn't have problems with the derivation. In case you have, you can try to wash it, even in the middle of the race with some water. There are lubrications for extreme conditions: try to obtain one. And of course: the tires are the most important part. Use ones with a lot of space of the grooves.
If you can, preride the track and practice on the specific moments. If you can't preride, do not risk if you are not secure. Slow down and stay on the safe side, rather than risk an injury.
Good luck and share with us what hapens.