Connell climate

Connell Frost Dates and Growing Season

NOAA 1991-2020 normals for Connell 1 W, 1.7 km from Connell, elevation 1020 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Connell 1 W. 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 30 and the first fall freeze around October 12, a growing season of about 165 days.

Median at 36°F
last May 13, first October 1
Median at 32°F
last April 30, first October 12
Median at 28°F
last April 10, 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 31May 24May 19May 16May 13May 10May 7May 3Apr 30
32°FMay 15May 10May 6May 2Apr 30Apr 27Apr 24Apr 19Apr 12
28°FMay 1Apr 26Apr 20Apr 15Apr 10Apr 6Apr 1Mar 29Mar 20
24°FApr 7Apr 1Mar 28Mar 22Mar 17Mar 13Mar 8Mar 2Feb 23
20°FMar 18Mar 10Mar 4Feb 28Feb 24Feb 18Feb 11Feb 4Jan 22
16°FMar 3Feb 25Feb 18Feb 10Feb 3Jan 27Jan 17Jan 7Dec 24

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 15Sep 22Sep 26Sep 29Oct 1Oct 3Oct 6Oct 9Oct 14
32°FSep 29Oct 3Oct 6Oct 9Oct 12Oct 15Oct 17Oct 21Oct 26
28°FOct 8Oct 14Oct 18Oct 22Oct 24Oct 27Oct 31Nov 3Nov 10
24°FOct 20Oct 25Oct 29Nov 1Nov 4Nov 9Nov 14Nov 20Nov 28
20°FOct 29Nov 4Nov 10Nov 17Nov 23Nov 28Dec 3Dec 10Dec 18
16°FNov 6Nov 14Nov 25Nov 30Dec 6Dec 12Dec 19Dec 28Jan 6

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°F159153148143139135131125117
32°F187179173169165161157152144
28°F222213207202197191187182173
24°F265252245239232226220214206
20°F314300290282273266259251240
16°F349336326316308301290280267

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
96% 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
5,450
Cooling degree days, base 65°F
610
Growing degree days, base 40°F
5,024
Growing degree days, base 45°F
3,766
Growing degree days, base 50°F
2,714
Growing degree days, base 55°F
1,848
Growing degree days, base 60°F
1,143

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January99501
February77003
March648015
April421186
May21026289
June6975456
July9238694
August16216665
September10654399
October4431101
November76606
December99701

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 1.7 km from Connell. 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 USC00451690 (Connell 1 W). Public domain.