The title says it. The bag of fertilizer Im using says to use every 3 weeks. There has been a lot of rain and I leave the pots outside. Thanks for the help.

If the pots has drainage hole it will drain the excess water and along with it the small amount of fertilizer.

I would recommend to wait and watch and check how the plants are growing before adding the another dose of fertilizer.
Overfertilizer is also not good for the plants. It damages the plants.

I agree. If you're applying every three weeks, it's going to make little difference. If it's raining that much, I'd watch the plant carefully for signs that it's too wet. Another reason not to change another part of the routine, so you can judge the effect of one thing, in this case, the frequent rain.