River Bend climate

River Bend Frost Dates and Growing Season

NOAA 1991-2020 normals for Perrytown, 5.8 km from River Bend, elevation 28 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Perrytown. 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 March 20 and the first fall freeze around November 20, a growing season of about 246 days.

Median at 36°F
last April 1, first November 7
Median at 32°F
last March 20, first November 20
Median at 28°F
last March 4, first December 6

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°FApr 17Apr 11Apr 6Apr 3Apr 1Mar 29Mar 26Mar 22Mar 17
32°FApr 5Mar 31Mar 27Mar 24Mar 20Mar 17Mar 13Mar 8Feb 28
28°FMar 23Mar 17Mar 12Mar 8Mar 4Feb 28Feb 25Feb 18Feb 6
24°FMar 11Mar 4Feb 28Feb 22Feb 15Feb 7Feb 1Jan 27Jan 15
20°FFeb 27Feb 18Feb 7Feb 1Jan 30Jan 23Jan 17Jan 10Dec 31
16°FFeb 15Feb 2Jan 30Jan 24Jan 19Jan 16Jan 10Jan 5Dec 30

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 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 17Nov 23
32°FNov 5Nov 10Nov 14Nov 17Nov 20Nov 24Nov 29Dec 3Dec 13
28°FNov 18Nov 23Nov 27Dec 1Dec 6Dec 13Dec 22Dec 31Jan 7
24°FDec 3Dec 9Dec 15Dec 24Dec 30Jan 4Jan 10Jan 16Jan 26
20°FDec 13Dec 24Dec 31Jan 4Jan 9Jan 14Jan 18Jan 25Feb 4
16°FDec 24Jan 1Jan 5Jan 9Jan 15Jan 18Jan 23Jan 29Feb 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°F244237231226222218213208201
32°F273264257251246241236230222
28°F310299292287280274268260251
24°F347334326317312305299293281
20°F365365363352344334327317304
16°F365365365365365365360347333

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
96% of years
20°F or colder
73% of years
16°F or colder
35% 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
2,560
Cooling degree days, base 65°F
1,851
Growing degree days, base 40°F
8,527
Growing degree days, base 45°F
6,873
Growing degree days, base 50°F
5,364
Growing degree days, base 55°F
4,019
Growing degree days, base 60°F
2,845

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January601170
February483484
March37014172
April14457370
May34167598
June1348796
July0465930
August0420885
September5272717
October10484447
November31014194
December5084101

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 5.8 km from River Bend. 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 USC00316676 (Perrytown). Public domain.