Riverton climate

Riverton Frost Dates and Growing Season

NOAA 1991-2020 normals for Pennsauken 1N, 5.1 km from Riverton, elevation 46 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pennsauken 1N. 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 31, a growing season of about 199 days.

Median at 36°F
last April 27, first October 19
Median at 32°F
last April 15, first October 31
Median at 28°F
last April 1, first November 10

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 15May 9May 4May 1Apr 27Apr 25Apr 22Apr 19Apr 14
32°FMay 1Apr 25Apr 20Apr 17Apr 15Apr 11Apr 8Apr 5Apr 1
28°FApr 14Apr 9Apr 6Apr 4Apr 1Mar 30Mar 27Mar 23Mar 17
24°FApr 2Mar 30Mar 25Mar 22Mar 19Mar 15Mar 12Mar 8Mar 2
20°FMar 22Mar 17Mar 13Mar 10Mar 6Mar 3Feb 28Feb 24Feb 17
16°FMar 12Mar 6Mar 2Feb 28Feb 24Feb 19Feb 13Feb 8Feb 1

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 6Oct 10Oct 14Oct 17Oct 19Oct 22Oct 26Oct 29Nov 1
32°FOct 16Oct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12
28°FOct 31Nov 2Nov 5Nov 8Nov 10Nov 13Nov 16Nov 20Nov 24
24°FNov 7Nov 11Nov 15Nov 18Nov 21Nov 25Nov 29Dec 3Dec 9
20°FNov 16Nov 22Nov 27Dec 1Dec 5Dec 10Dec 15Dec 21Dec 31
16°FDec 1Dec 7Dec 13Dec 20Dec 24Dec 29Jan 2Jan 9Jan 17

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°F195188183178174170165159152
32°F218211207203199194189185177
28°F243235231227223219215210204
24°F272262256252247242238233226
20°F300290283277272267261256249
16°F329318311306302297289283274

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
4,858
Cooling degree days, base 65°F
1,171
Growing degree days, base 40°F
6,163
Growing degree days, base 45°F
4,857
Growing degree days, base 50°F
3,711
Growing degree days, base 55°F
2,720
Growing degree days, base 60°F
1,872

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00305
February85105
March706132
April37313152
May13763393
June18229661
July0385849
August1319783
September43143551
October29218218
November582049
December851012

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 5.1 km from Riverton. 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 USC00286864 (Pennsauken 1N). Public domain.