Roselle climate

Roselle Frost Dates and Growing Season

NOAA 1991-2020 normals for Cranford, 5.7 km from Roselle, elevation 80 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cranford. 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 11 and the first fall freeze around October 31, a growing season of about 202 days.

Median at 36°F
last April 25, first October 20
Median at 32°F
last April 11, first October 31
Median at 28°F
last March 30, first November 12

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 11May 5May 1Apr 28Apr 25Apr 22Apr 19Apr 15Apr 10
32°FApr 28Apr 22Apr 18Apr 15Apr 11Apr 8Apr 5Apr 2Mar 30
28°FApr 12Apr 7Apr 4Apr 1Mar 30Mar 27Mar 23Mar 19Mar 14
24°FApr 2Mar 29Mar 25Mar 21Mar 18Mar 15Mar 12Mar 8Mar 1
20°FMar 24Mar 18Mar 14Mar 10Mar 7Mar 4Feb 28Feb 24Feb 16
16°FMar 13Mar 6Mar 2Feb 28Feb 24Feb 19Feb 12Feb 5Jan 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 7Oct 10Oct 14Oct 17Oct 20Oct 23Oct 27Oct 31Nov 4
32°FOct 14Oct 20Oct 25Oct 28Oct 31Nov 3Nov 6Nov 9Nov 15
28°FOct 27Nov 1Nov 4Nov 9Nov 12Nov 15Nov 18Nov 23Dec 1
24°FNov 10Nov 15Nov 19Nov 22Nov 26Nov 30Dec 3Dec 7Dec 15
20°FNov 21Nov 28Dec 2Dec 6Dec 11Dec 15Dec 20Dec 25Jan 2
16°FDec 6Dec 13Dec 19Dec 23Dec 28Jan 1Jan 5Jan 11Jan 20

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°F198190185181176172169164156
32°F222216210206202198193188180
28°F251243238232228223218214207
24°F280270264259253249244238231
20°F305296291285280275270264254
16°F334323315310306300296287278

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
99% 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
4,856
Cooling degree days, base 65°F
1,123
Growing degree days, base 40°F
6,101
Growing degree days, base 45°F
4,795
Growing degree days, base 50°F
3,648
Growing degree days, base 55°F
2,659
Growing degree days, base 60°F
1,816

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00303
February84303
March715129
April38412144
May14558380
June19217648
July0364829
August1317781
September46140545
October29014216
November563056
December848013

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 5.7 km from Roselle. 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 USC00282023 (Cranford). Public domain.