How long for thermals to start working after rain?

I am looking out the window of my office in Salt Lake City, Utah right
now to rain falling. Tomorrow is expected to be in the mid to upper
60's and sunny with fairly low humidity. Might be a decent soaring
day. How long does it take the ground to dry up enough after rain for
thermal soaring conditions to get good again? I am sure the answer
might be different when the temps are in the 60's and 70's compared to
80's and 90's summer time. What have you all experienced?

Thanks,
Bruno - B4