Jerome climate

Jerome Frost Dates and Growing Season

NOAA 1991-2020 normals for Springfield #2, 3.2 km from Jerome, elevation 599 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Springfield #2. 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 15 and the first fall freeze around October 22, a growing season of about 188 days.

Median at 36°F
last April 27, first October 13
Median at 32°F
last April 15, first October 22
Median at 28°F
last April 5, first November 1

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 13May 7May 3Apr 30Apr 27Apr 24Apr 20Apr 17Apr 13
32°FApr 30Apr 24Apr 20Apr 18Apr 15Apr 12Apr 10Apr 7Apr 3
28°FApr 19Apr 14Apr 10Apr 7Apr 5Apr 3Mar 31Mar 28Mar 21
24°FApr 9Apr 4Apr 1Mar 30Mar 26Mar 22Mar 19Mar 15Mar 10
20°FMar 31Mar 26Mar 22Mar 18Mar 15Mar 12Mar 9Mar 4Feb 26
16°FMar 21Mar 16Mar 14Mar 10Mar 7Mar 3Feb 28Feb 22Feb 14

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 29Oct 4Oct 7Oct 10Oct 13Oct 15Oct 17Oct 20Oct 23
32°FOct 9Oct 15Oct 17Oct 20Oct 22Oct 24Oct 27Oct 30Nov 2
28°FOct 20Oct 25Oct 28Oct 30Nov 1Nov 3Nov 7Nov 10Nov 15
24°FOct 31Nov 2Nov 6Nov 9Nov 12Nov 15Nov 19Nov 23Nov 29
20°FNov 7Nov 11Nov 15Nov 19Nov 23Nov 26Dec 1Dec 4Dec 9
16°FNov 15Nov 20Nov 25Nov 29Dec 1Dec 6Dec 9Dec 15Dec 21

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°F185180175171167164160154147
32°F206200196192188184180175169
28°F230224219215210207203198191
24°F254247241237232227223218211
20°F276269262257252248243238230
16°F296287280274269265261254247

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
5,455
Cooling degree days, base 65°F
1,094
Growing degree days, base 40°F
5,947
Growing degree days, base 45°F
4,706
Growing degree days, base 50°F
3,608
Growing degree days, base 55°F
2,636
Growing degree days, base 60°F
1,796

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,17102
February94208
March733453
April37711163
May13884415
June11240679
July2334797
August6278738
September72122502
October33121207
November668140
December1,00605

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 3.2 km from Jerome. 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 USC00118186 (Springfield #2). Public domain.