Growing Degree Days in Alabama

Alabama has accumulated about 3801 growing degree days (base 50°F, since January 1), averaged across 19 NOAA USCRN stations. Station totals range from 3067 to 4368 GDD. The total climbs through summer and levels off as temperatures fall.

These are base 50°F growing degree days accumulated from January 1, the turf-industry convention. Each day adds the amount its average air temperature runs above 50°F, floored at zero. Totals from a different base or start date are not interchangeable, so the model is stated explicitly wherever a number appears.

Turf managers track the running total to time temperature-driven tasks: crabgrass pre-emergent before germination, annual bluegrass seedhead suppression, plant growth regulator reapplication, and grub control. Growing degree days are a timing signal read against a model, not a fixed calendar date.

Alabama has banked 3811 GDD (base 50°F) through August 16. That is 98 GDD ahead of 2025, when Alabama had banked 3713 GDD by August 16, based on 17 stations with records for both years.

This page reads Alabama's accumulation against the published turf models, each on its own base temperature and start date: Michigan State's crabgrass pre-emergent timer (250 to 500 GDD base 32°F from February 15) and germination timer (200 to 600 GDD base 50°F), Purdue's spring broadleaf windows by formulation, Iowa State's Japanese beetle emergence range, and the professional models for annual bluegrass seedhead suppression, early-season dollar spot, and growth regulator intervals. A target range means nothing without its base and start date, so both travel with every number.