should we ask the problem you are trying to solve.. before we encourage use of anything???

my gut tells me they are contacts remedies ... as compared to preventative... but sometimes my gut lies to me ...

if you dont have a current problem.. then you shouldnt be using anything, regardless of the humidity & temps ... eh???

ken

Shouldn't be a problem with soap. The general rule for ALL pesticides is temps >80F ...or the sum of the temp AND humidity is >140. With soaps in particular though, you should still be able to spray in the evening and rinse off in the morning, regardless of the numbers. Since it's a contact pesticide, a couple hours on the plant's surface's is usually good enough and rinsing will decrease the odds of damage from the sun.

Kevin

There is no way to give an answer to this question since it depends on far too many factors for any answer.
1. Never apply any insecticide when temperatures are too high (read the label for that).
2. Never apply any insecticide in the absence of the target insect.
I have, on rare occasion, applied Insecticidal Soap early in the morning (6:00 am) when humidity was high but the temperature was still below 80 with good results if the plants have been attacked by a pest. That is also a good time since the beneficials are seldom out and about them either and the targets are often slow and sluggish.