Caldwell climate

Caldwell Frost Dates and Growing Season

NOAA 1991-2020 normals for Wellington, 31 km from Caldwell, elevation 1224 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wellington. 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 29, a growing season of about 195 days.

Median at 36°F
last April 24, first October 18
Median at 32°F
last April 15, first October 29
Median at 28°F
last April 3, first November 5

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 6May 2Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 9
32°FApr 30Apr 25Apr 21Apr 18Apr 15Apr 11Apr 8Apr 3Mar 29
28°FApr 20Apr 14Apr 10Apr 6Apr 3Mar 31Mar 27Mar 21Mar 15
24°FApr 11Apr 4Mar 31Mar 26Mar 20Mar 16Mar 12Mar 8Mar 2
20°FMar 30Mar 22Mar 16Mar 11Mar 7Mar 4Feb 28Feb 25Feb 20
16°FMar 16Mar 10Mar 6Mar 2Feb 28Feb 24Feb 20Feb 15Feb 5

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°FOct 2Oct 9Oct 12Oct 15Oct 18Oct 20Oct 23Oct 27Nov 1
32°FOct 14Oct 19Oct 22Oct 25Oct 29Nov 1Nov 2Nov 5Nov 10
28°FOct 22Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16Nov 21
24°FOct 31Nov 4Nov 8Nov 11Nov 15Nov 19Nov 23Nov 27Dec 2
20°FNov 7Nov 11Nov 17Nov 20Nov 24Nov 28Dec 1Dec 5Dec 12
16°FNov 15Nov 22Nov 26Dec 1Dec 4Dec 9Dec 14Dec 19Dec 27

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°F197190184180176172168163156
32°F217210204199195190186181174
28°F238230224219214210206201194
24°F263254248243237232227220212
20°F286278271266261255249243233
16°F310302295289283277271264255

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
4,543
Cooling degree days, base 65°F
1,642
Growing degree days, base 40°F
6,988
Growing degree days, base 45°F
5,636
Growing degree days, base 50°F
4,429
Growing degree days, base 55°F
3,365
Growing degree days, base 60°F
2,437

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January99703
February788014
March575384
April30719214
May96113485
June6324768
July0482947
August1438902
September37217631
October23444306
November580271
December92206

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 31 km from Caldwell. 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 USC00148670 (Wellington). Public domain.