Dalzell climate

Dalzell Frost Dates and Growing Season

NOAA 1991-2020 normals for Peru, 5.8 km from Dalzell, elevation 620 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Peru. 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 24 and the first fall freeze around October 18, a growing season of about 176 days.

Median at 36°F
last May 4, first October 6
Median at 32°F
last April 24, first October 18
Median at 28°F
last April 13, first October 28

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

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 23Sep 28Oct 1Oct 4Oct 6Oct 10Oct 12Oct 16Oct 20
32°FOct 3Oct 9Oct 12Oct 15Oct 18Oct 20Oct 22Oct 25Oct 28
28°FOct 16Oct 21Oct 23Oct 25Oct 28Oct 30Nov 1Nov 3Nov 8
24°FOct 28Oct 31Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 21
20°FNov 4Nov 8Nov 12Nov 15Nov 18Nov 21Nov 24Nov 29Dec 3
16°FNov 11Nov 16Nov 20Nov 23Nov 26Nov 30Dec 3Dec 7Dec 15

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°F173168164159155150146141134
32°F194188183179176172167162154
28°F217210206201197194190185179
24°F240234228224220216212207201
20°F262254249245240236231226220
16°F281272268263258253249243236

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
6,420
Cooling degree days, base 65°F
838
Growing degree days, base 40°F
5,262
Growing degree days, base 45°F
4,129
Growing degree days, base 50°F
3,121
Growing degree days, base 55°F
2,230
Growing degree days, base 60°F
1,466

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33301
February1,09101
March857226
April4776107
May19062349
June27187611
July4265725
August10212666
September10193446
October40012162
November774026
December1,15602

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 Dalzell. 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 USC00116753 (Peru). Public domain.