First Day Of Summer 2024 Canada Time. In 2024, the summer solstice will occur on june 20, at 20:51 gmt in the northern hemisphere, and on december 21, at 09:20 gmt in the southern hemisphere. The summer solstice is also known as the longest day, which is perhaps the most notable feature.

On that day, the autumnal equinox will occur, marking the beginning of fall. This is the first day of astronomical summer and occurs as the sun reaches its most.