Metropolis climate

Metropolis Frost Dates and Growing Season

NOAA 1991-2020 normals for Brookport Dam 52, 7.5 km from Metropolis, elevation 330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Brookport Dam 52. 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 6 and the first fall freeze around October 27, a growing season of about 203 days.

Median at 36°F
last April 19, first October 18
Median at 32°F
last April 6, first October 27
Median at 28°F
last March 27, first November 5

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 4Apr 29Apr 25Apr 22Apr 19Apr 15Apr 11Apr 8Apr 3
32°FApr 23Apr 17Apr 12Apr 9Apr 6Apr 3Mar 31Mar 28Mar 21
28°FApr 11Apr 6Apr 3Mar 31Mar 27Mar 24Mar 20Mar 15Mar 8
24°FApr 4Mar 29Mar 24Mar 20Mar 16Mar 12Mar 8Mar 2Feb 25
20°FMar 22Mar 17Mar 13Mar 8Mar 4Mar 1Feb 25Feb 20Feb 11
16°FMar 16Mar 7Mar 2Feb 26Feb 22Feb 16Feb 10Feb 5Jan 31

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 13Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
32°FOct 15Oct 20Oct 23Oct 25Oct 27Oct 30Nov 1Nov 4Nov 9
28°FOct 24Oct 28Oct 31Nov 2Nov 5Nov 7Nov 11Nov 14Nov 21
24°FNov 1Nov 6Nov 9Nov 13Nov 16Nov 20Nov 24Dec 1Dec 4
20°FNov 10Nov 15Nov 20Nov 24Nov 28Dec 1Dec 5Dec 11Dec 20
16°FNov 20Nov 27Dec 1Dec 5Dec 11Dec 16Dec 22Dec 28Jan 5

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°F203196191186182177174168161
32°F224216210207203200195190182
28°F247239232227223218214209204
24°F271263257252246242236229220
20°F298288281274268262257252243
16°F323314307300294288280274263

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
4,267
Cooling degree days, base 65°F
1,481
Growing degree days, base 40°F
6,989
Growing degree days, base 45°F
5,602
Growing degree days, base 50°F
4,362
Growing degree days, base 55°F
3,260
Growing degree days, base 60°F
2,298

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January959010
February763018
March565486
April24927261
May70122518
June4302748
July0415880
August1379843
September31190609
October23039299
November554274
December842017

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 7.5 km from Metropolis. 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 USC00110993 (Brookport Dam 52). Public domain.