Temps in the 60s even 50s and rain is wet gold for plants. Rain water is better than any water you can give your plants. Because I have lived in a cold climate and have pushed the limits I have found very few plants that fall over and die from rain water even chilly rain water.
I know you warm people think 50s and 60s is cold but it really is not.
Cool and rain is the best thing for plants because heat stress plants. Where as cool and moisture relaxes them to drink and grow. Notice I said cool not cold.