I thought of this question after a week of jogging, where each day after it rained, the temperature seemed warmer. I also noted this as a lifeguard where, after closing the pool due to thunder, we would go for a swim and the downpour actually seemed to warm the pool.
I haven't really attempted much prior research as the whole phenomenon seems to be influence by a number of variables I may be blind to or lack complete knowledge of. Such as
- How humidity may play into this
- Whether the drops begin to burden the cloud after a certain part turns into liquid form or the mass together is cooled and weighted as so
- How air density may play a role into this
- Types of Water and acidity
- Energy exposed to