Gilbert climate

Gilbert Frost Dates and Growing Season

NOAA 1991-2020 normals for Ames 8 Wsw, 14 km from Gilbert, elevation 1099 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ames 8 Wsw. 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 April 23 and the first fall freeze around October 14, a growing season of about 173 days.

Median at 36°F
last May 3, first October 4
Median at 32°F
last April 23, first October 14
Median at 28°F
last April 11, first October 24

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°FMay 14May 10May 7May 5May 3May 1Apr 28Apr 25Apr 19
32°FMay 5May 2Apr 30Apr 26Apr 23Apr 20Apr 16Apr 12Apr 7
28°FApr 27Apr 22Apr 19Apr 14Apr 11Apr 8Apr 6Apr 3Mar 30
24°FApr 19Apr 12Apr 8Apr 5Apr 3Mar 31Mar 29Mar 24Mar 19
20°FApr 10Apr 5Apr 1Mar 29Mar 25Mar 21Mar 18Mar 13Mar 9
16°FApr 1Mar 28Mar 23Mar 19Mar 15Mar 12Mar 10Mar 6Mar 2

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°FSep 21Sep 26Sep 29Oct 1Oct 4Oct 6Oct 9Oct 12Oct 17
32°FSep 29Oct 4Oct 7Oct 11Oct 14Oct 17Oct 19Oct 22Oct 27
28°FOct 9Oct 15Oct 19Oct 22Oct 24Oct 26Oct 29Nov 1Nov 5
24°FOct 20Oct 25Oct 28Oct 30Nov 2Nov 4Nov 6Nov 9Nov 15
20°FOct 29Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 20Nov 26
16°FNov 4Nov 8Nov 11Nov 15Nov 18Nov 21Nov 25Nov 28Dec 4

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°F172166162158155151148143137
32°F193185180176173169166161155
28°F212205200196193189185180174
24°F231224218214211206202198191
20°F250243238232228223219213205
16°F267260254249245242238231222

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
6,521
Cooling degree days, base 65°F
892
Growing degree days, base 40°F
5,386
Growing degree days, base 45°F
4,255
Growing degree days, base 50°F
3,235
Growing degree days, base 55°F
2,330
Growing degree days, base 60°F
1,545

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,38200
February1,12401
March847128
April4498125
May16963370
June19202633
July3282744
August9220676
September96103461
October39314173
November809024
December1,22101

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 14 km from Gilbert. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00130200 (Ames 8 Wsw). Public domain.