Carthage climate

Carthage Frost Dates and Growing Season

NOAA 1991-2020 normals for Watertown, 21.3 km from Carthage, elevation 497 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Watertown. 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 May 2 and the first fall freeze around October 13, a growing season of about 163 days.

Median at 36°F
last May 13, first October 2
Median at 32°F
last May 2, first October 13
Median at 28°F
last April 22, first October 25

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 27May 23May 19May 16May 13May 10May 7May 3Apr 30
32°FMay 17May 12May 8May 5May 2Apr 30Apr 27Apr 24Apr 20
28°FMay 6May 2Apr 29Apr 24Apr 22Apr 19Apr 16Apr 13Apr 8
24°FApr 23Apr 19Apr 17Apr 14Apr 11Apr 8Apr 6Apr 3Mar 31
20°FApr 16Apr 11Apr 7Apr 5Apr 2Apr 1Mar 30Mar 25Mar 20
16°FApr 7Apr 3Mar 31Mar 30Mar 27Mar 23Mar 20Mar 17Mar 12

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 21Sep 25Sep 28Oct 1Oct 2Oct 5Oct 7Oct 11Oct 17
32°FOct 1Oct 3Oct 6Oct 9Oct 13Oct 16Oct 19Oct 23Oct 28
28°FOct 10Oct 16Oct 19Oct 23Oct 25Oct 28Oct 31Nov 3Nov 7
24°FOct 23Oct 27Oct 31Nov 2Nov 4Nov 7Nov 10Nov 13Nov 18
20°FNov 1Nov 6Nov 10Nov 12Nov 15Nov 18Nov 21Nov 24Nov 29
16°FNov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 3Dec 8

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°F160155150147143139135130124
32°F181176171167163159155151145
28°F204198192188184180176171165
24°F224217213209206202199195188
20°F245238234229226222217213207
16°F262255251247243239235231224

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
7,293
Cooling degree days, base 65°F
559
Growing degree days, base 40°F
4,521
Growing degree days, base 45°F
3,469
Growing degree days, base 50°F
2,547
Growing degree days, base 55°F
1,753
Growing degree days, base 60°F
1,084

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40101
February1,22400
March1,06707
April632252
May27731252
June69102484
July13195648
August22164608
September14859369
October4765108
November797019
December1,16901

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 21.3 km from Carthage. 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 USC00309000 (Watertown). Public domain.