In 2025, summer in the Northern Hemisphere officially begins on Friday, June 20, 2025, with the summer solstice, and ends on Monday, September 22, 2025, by astronomical definition.

Many calendars and planners also treat “summer 2025” in a practical, day‑to‑day sense as running through June, July, and August 2025 (June 1 to August 31).

So if you’re planning vacations or events, you can think of summer 2025 as:

  • “Official” astronomical summer: June 20–September 22, 2025.
  • Everyday/meteorological summer: June 1–August 31, 2025.

TL;DR: Summer 2025 starts June 20 by the solstice, but most people treat it as June–August.✅