For , summer 2025–2026 begins on: December 21, 2025 (most years, though occasionally December 22 depending on the year and time zone).
In the Southern Hemisphere, summer officially starts on the (between December 20–23).
If you meant (end of year), the same December solstice applies.
MODELLER (copyright © 1989-2026 Andrej Sali) is
maintained by Ben Webb
at the Departments of Biopharmaceutical Sciences and Pharmaceutical Chemistry,
and California Institute for Quantitative Biomedical Research, Mission Bay
Byers Hall, University of California San Francisco, San Francisco,
CA 94143, USA.
Any selling or distribution of the program or its parts, original or modified,
is prohibited without a written permission from Andrej Sali.
This file last modified: Thu Jan 29 12:28:54 PST 2026.