Fall won't officially begin until Monday, September 23, the day of the Autumnal Equinox, but as far as meteorologists are concerned, summer is already in the books. For stat-keeping purposes, meteorologists define the summer season as the three-month period of June, July, and August, or June 1st through August 31st. This summer, overall rainfall was 10. 51", or just 0. 02" below average. Rainfall this summer compared to average. We can dig a little bit deeper than that, though.