Heavy rain and thunder normally comes in the late afternoon when heat from the sun has built up, but that could change later this century
Source:
https://www.newscientist.com/article/2205094-climate-change-may-mean-heavy-rain-falls-in-the-early-morning/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home