Birch Tree climate

Birch Tree Frost Dates and Growing Season

NOAA 1991-2020 normals for Winona 3 Sw, 9.7 km from Birch Tree, elevation 961 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winona 3 Sw. 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 18, a growing season of about 176 days.

Median at 36°F
last May 1, first October 8
Median at 32°F
last April 22, first October 18
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 14May 10May 6May 3May 1Apr 29Apr 26Apr 22Apr 17
32°FMay 6May 1Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 8
28°FApr 26Apr 21Apr 17Apr 13Apr 10Apr 7Apr 4Mar 31Mar 24
24°FApr 15Apr 9Apr 4Apr 1Mar 29Mar 24Mar 20Mar 15Mar 8
20°FApr 3Mar 28Mar 21Mar 17Mar 14Mar 10Mar 6Mar 1Feb 24
16°FMar 21Mar 14Mar 10Mar 5Mar 1Feb 27Feb 22Feb 15Feb 6

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 27Oct 1Oct 3Oct 6Oct 8Oct 10Oct 13Oct 16Oct 20
32°FOct 5Oct 9Oct 12Oct 15Oct 18Oct 20Oct 22Oct 25Oct 28
28°FOct 15Oct 19Oct 22Oct 25Oct 27Oct 30Nov 1Nov 4Nov 9
24°FOct 24Oct 29Nov 1Nov 4Nov 6Nov 10Nov 14Nov 19Nov 25
20°FNov 1Nov 6Nov 11Nov 16Nov 20Nov 25Nov 29Dec 3Dec 10
16°FNov 11Nov 20Nov 26Dec 1Dec 4Dec 8Dec 13Dec 20Dec 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°F174169165162158155152148140
32°F196189185180176173169164157
28°F221213206202198194190185178
24°F250241235230224219213208201
20°F277268261254249243237231222
16°F306296288282276271265257246

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
5,029
Cooling degree days, base 65°F
1,034
Growing degree days, base 40°F
5,972
Growing degree days, base 45°F
4,693
Growing degree days, base 50°F
3,565
Growing degree days, base 55°F
2,582
Growing degree days, base 60°F
1,739

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,04302
February819012
March653154
April3636162
May13565403
June11203642
July1339803
August3293755
September77110484
October33317204
November645141
December94705

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 9.7 km from Birch Tree. 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 USC00239056 (Winona 3 Sw). Public domain.