Growing Degree Days in Alabama

Alabama has accumulated about 5195 growing degree days (base 50°F, since January 1), averaged across 14 NOAA USCRN stations. Station totals range from 4458 to 5688 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 5195 GDD (base 50°F) through September 30. That is 292 GDD ahead of 2025, when Alabama had banked 4903 GDD by September 30, based on 14 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.