[paul.fr]

I have noticed that there are far more thunder storms in the late afternoon and night, than there are during the daytime. Am i imagining this or is there a perfectly good scientific reason behind it?

[elegantlywasted]

It might have something to do with when the humidity is at the highest point?

[kdlynn]

i have noticed it too. morning thunderstorms are rare, but they do happen, and i love them!

[JP]

It might have something to do with when the humidity is at the highest point?

My best guess: The air can absorb more humidity when it's warmer, and less when it's cooler.  During the mid-day hours, the air is the hottest and absorbs a lot of water.  Then when the air starts to cool later in the day, it can't hold all that water, and it begins to condense as clouds, leading to rain and thunderstorms.

[another_someone]

Thunderstorms are not always associated with rain, although they clearly are associated with dense cloud, which significantly increases the likelihood of rain.

From what I can ascertain, thunderstorms require up updraught of warm air into colder air, which would seem more probable when the air is cooling over ground that is still warm from the day.