Normally, I'm hesitant to fertilize during the height of summer, since it could burn your plants. The grounds being saturated today may dry up rather quickly when the sun is out. However, I am faced with my yard long beans getting fairly pale lately and so I am considering using a weak solution to see if there can be any improvement. So all I can say, is experiment very carefully and err on the side of a weak solution.

Good evening appletreasure
After a rain is the perfect time to fertilize. The ground or soil or whatever ya grow in should always be wet when ya give ferts.
I fertilize all the time[ every other week ] just water first then wait about an hr and then fert,just don`t do it dry or as pointed out by Ianna , you`ll fry your plants.
If it`s been a while just give em 1/2 strength.
Hope this helps ya some.
cowboyal