It is better if you do not take the chance.
Sealers cure more slowly when moisture is in the air. The label gives "approximate" drying/curing times. If the sealer has time to fully cure, rain is no problem. The more you take on risk by "pushing the envelope", the more chance there is for something to occur that normally would not even be known and not a problem.
If you choose to do it anyway and a problem does occur, check the web site "Problem Solving" section to identify the problem and how to proceed to solve it. Note that you can be looking at different things (i.e. mineral water spots on top, moisture trapped temporarily below, efflorescence below, minerals washed out from planters, etc.). It should not be a disaster and you might not need to do anything.
If the sealer surface is actually dimpled by rain falling when still wet, or damaged for some other reason, see sealer label about how to repair.