I am pretty sure about barometric pressure playing a role in natural conditions for them to start activity.

That's my point, i am in the Northern Hemisphere, here December is a rainy month so i would play only with higher temperatures of course, and then I would start feeling adjusted accordingly to African calendar(that's what i mean with mimicking)
I have seen several times toads like Bufo bufo or B.calamita a few hours before first rains.
How can that be possible ? ( fields don't have a single drop of rain yet, and they come out).
I found also that is very old popular sense people saying -If you see a toad it's going to rain !