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Growing Degree Days in California

California has accumulated about 3361 GDD so far this year (base 50°F, since January 1), averaged across 6 NOAA USCRN stations. Station totals range from 1095 to 7441 GDD. Through August 16, 2026. That is 163 GDD ahead of 2025, when California had banked 3198 GDD by August 16, based on 6 stations with records for both years.

How to Read This Number

Growing degree days count accumulated heat: each day adds the amount its average temperature runs above 50°F, the point where cool-season growth and most pests get going. Turf managers use the running total to time crabgrass pre-emergent, annual bluegrass seedhead suppression, plant growth regulator reapplication, and grub control. Treat it as a timing signal read against a model, not a fixed date. The total here is measured air temperature from NOAA USCRN stations, base 50°F, accumulated from January 1 — state the model whenever you compare totals, because a different base or start date is not interchangeable.

USCRN Stations in California (6)

StationGDD (base 50°F)Through
Stovepipe Wells 1 SW7,441Aug 16
Fallbrook 5 NE4,078Aug 16
Redding 12 WNW3,415Aug 16
Santa Barbara 11 W2,391Aug 16
Yosemite Village 12 W1,746Aug 16
Merced 23 WSW1,095Aug 16

Timing Windows for California

Where California sits against the published turf models. Each model carries its own base temperature and start date, so the accumulation column differs from row to row. A status of “varies by area” means the state’s coldest and warmest stations fall on opposite sides of the window.

Show
ModelTargetCalifornia nowStatus
Crabgrass pre-emergent timerbase 32°F, from Feb 15250 to 500 GDD1,885 to 10,358Passed
Crabgrass germination timerbase 50°F, from Feb 15200 to 600 GDD1,075 to 7,065Passed
Spring broadleaf herbicide timerbase 50°F, from Feb 15110 to 150 GDD, 150 to 200 GDD, 200 to 600 GDDby formulation1,075 to 7,065Passed
Japanese beetle adult emergencebase 50°F, from Jan 11030 to 2150 GDD1,095 to 7,441Varies by area
Poa annua seedhead suppression (Proxy/Primo)base 32°F, from Feb 15200 to 500 GDD1,885 to 10,358Passed
Poa annua seedhead suppression (Embark)base 22°F, from Feb 15680 to 1050 GDD2,335 to 12,188Passed
Poa annua seedhead flushbase 22°F, from Feb 151050 to 2900 GDD2,335 to 12,188Varies by area
Early-season dollar spot DMI applicationbase 50°F, from Feb 15140 to 175 GDD1,075 to 7,065Passed
Growth regulator reapplication intervalbase 32°F, from Feb 15200 GDD1,885 to 10,358Spacing, not a date
Broadleaf weed flowering timingsbase 50°F, from Feb 15Reference only1,075 to 7,065Reference
Legacy 50/86 modelbase 50°F / 86°F ceiling, from Feb 15Reference only880 to 5,555Reference

Turf professional models are hidden by default. They cover putting greens and fairways rather than home lawns.

Michigan State ground-truthed these models in the Great Lakes region and does not recommend them for the mid-south transition zone or the South. Outside the Upper Midwest and Northeast, read them as a guide and confirm against local extension guidance.

How California Accumulated This Year

Most recent 14 reporting days

Daily and running totals, averaged across the state's 6 reporting stations. Days a station did not report are left out rather than counted as zero, so the dates can skip.

DateDailyTotal (base 50°F)Total (base 32°F)
Aug 331.52,9706,154
Aug 4323,0026,204
Aug 530.73,0336,252
Aug 6323,0656,302
Aug 734.53,0996,355
Aug 834.83,1346,408
Aug 934.83,1696,460
Aug 1033.23,2026,512
Aug 1130.83,2336,561
Aug 1228.43,2616,607
Aug 1325.13,2866,650
Aug 1424.43,3116,692
Aug 1524.43,3356,735
Aug 1625.93,3616,779

Month by month, against last year

GDD earned in each month at base 50°F, this year beside 2025.

Month20262025Base 32°F (2026)
January17175678
February195159638
March4851861,029
April335303827
May5175411,058
June7057091,234
July8377891,365
August487866775
September—712—
October—443—
November—254—
December—162—

Cities in California (314)

Each city page pairs the current soil temperature from its nearest monitoring station with a local growing-degree-day total where a NOAA USCRN station is close enough to measure one.

Growing Degree Days FAQ for California

How many growing degree days has California accumulated this year?

California has accumulated about 3361 growing degree days (base 50°F, since January 1), averaged across 6 NOAA USCRN stations. Station totals range from 1095 to 7441 GDD. The total climbs through summer and levels off as temperatures fall.

What base temperature and start date are these totals?

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.

What are growing degree days used for in lawn care?

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.

How does California compare to last year?

California has banked 3361 GDD (base 50°F) through August 16. That is 163 GDD ahead of 2025, when California had banked 3198 GDD by August 16, based on 6 stations with records for both years.

Which growing degree day models does this page track for California?

This page reads California'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.

See growing degree days for every state, read the growing degree days lawn-care guide, or browse the full California soil temperature directory.