Roseville climate

Roseville Frost Dates and Growing Season

NOAA 1991-2020 normals for Avon, 20.1 km from Roseville, elevation 640 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Avon. 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 22 and the first fall freeze around October 19, a growing season of about 177 days.

Median at 36°F
last May 2, first October 9
Median at 32°F
last April 22, first October 19
Median at 28°F
last April 10, first October 27

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 16May 11May 7May 4May 2Apr 29Apr 26Apr 22Apr 17
32°FMay 8May 3Apr 29Apr 25Apr 22Apr 19Apr 16Apr 12Apr 7
28°FApr 28Apr 22Apr 17Apr 13Apr 10Apr 7Apr 5Apr 2Mar 26
24°FApr 15Apr 9Apr 5Apr 2Mar 31Mar 28Mar 22Mar 17Mar 12
20°FApr 5Mar 31Mar 27Mar 23Mar 19Mar 16Mar 13Mar 8Mar 3
16°FMar 29Mar 22Mar 18Mar 14Mar 11Mar 8Mar 4Mar 1Feb 23

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 24Sep 29Oct 3Oct 6Oct 9Oct 11Oct 13Oct 16Oct 21
32°FOct 5Oct 10Oct 13Oct 16Oct 19Oct 21Oct 23Oct 25Oct 29
28°FOct 14Oct 19Oct 22Oct 25Oct 27Oct 30Nov 1Nov 5Nov 10
24°FOct 26Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 24
20°FNov 3Nov 8Nov 11Nov 15Nov 19Nov 22Nov 27Nov 30Dec 6
16°FNov 11Nov 16Nov 21Nov 26Nov 29Dec 1Dec 5Dec 9Dec 16

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°F175169165161157153150145140
32°F195190185181177173169164158
28°F219211206202199194190184177
24°F243235230225221217212207200
20°F265258252246241237232227220
16°F285275270265261255250243235

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
6,438
Cooling degree days, base 65°F
765
Growing degree days, base 40°F
5,180
Growing degree days, base 45°F
4,050
Growing degree days, base 50°F
3,044
Growing degree days, base 55°F
2,158
Growing degree days, base 60°F
1,391

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33600
February1,09103
March859130
April4724109
May19158346
June22165592
July6254713
August13200652
September10471419
October41512156
November782024
December1,14901

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 20.1 km from Roseville. 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 USC00110356 (Avon). Public domain.