Hill County climate

Hill County Frost Dates and Growing Season

NOAA 1991-2020 normals for Gildford, 15.8 km from Hill County, elevation 2820 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Gildford. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around May 24 and the first fall freeze around September 15, a growing season of about 114 days.

Median at 36°F
last June 7, first September 2
Median at 32°F
last May 24, first September 15
Median at 28°F
last May 12, first September 26

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FJun 26Jun 19Jun 14Jun 11Jun 7Jun 5Jun 1May 30May 25
32°FJun 7Jun 2May 31May 27May 24May 21May 19May 16May 12
28°FMay 27May 21May 17May 14May 12May 9May 6May 3Apr 29
24°FMay 11May 8May 5May 2Apr 30Apr 28Apr 25Apr 22Apr 16
20°FMay 4Apr 30Apr 26Apr 23Apr 20Apr 16Apr 13Apr 9Apr 5
16°FApr 29Apr 22Apr 18Apr 14Apr 10Apr 6Apr 2Mar 29Mar 20

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FAug 15Aug 21Aug 25Aug 29Sep 2Sep 4Sep 7Sep 10Sep 15
32°FAug 29Sep 4Sep 8Sep 12Sep 15Sep 18Sep 21Sep 24Sep 28
28°FSep 12Sep 17Sep 20Sep 23Sep 26Sep 28Oct 1Oct 3Oct 6
24°FSep 20Sep 25Sep 28Oct 1Oct 3Oct 5Oct 8Oct 12Oct 17
20°FSep 29Oct 3Oct 6Oct 10Oct 14Oct 16Oct 19Oct 23Oct 27
16°FOct 5Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 7

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F1059994898580756960
32°F13112512011711411010510092
28°F153148143140136133129124117
24°F175168163159155151148143136
20°F198191184179176171167162154
16°F219212206200195190186178171

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
8,720
Cooling degree days, base 65°F
247
Growing degree days, base 40°F
3,433
Growing degree days, base 45°F
2,495
Growing degree days, base 50°F
1,701
Growing degree days, base 55°F
1,055
Growing degree days, base 60°F
568

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48300
February1,25300
March1,07303
April695020
May4143128
June17823300
July50113528
August7897487
September30211197
October710036
November1,08002
December1,40600

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 15.8 km from Hill County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00243530 (Gildford). Public domain.