Lisbon climate

Lisbon Frost Dates and Growing Season

NOAA 1991-2020 normals for Cedar Rapids #1, 22.1 km from Lisbon, elevation 813 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cedar Rapids #1. 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 28 and the first fall freeze around October 12, a growing season of about 166 days.

Median at 36°F
last May 7, first October 2
Median at 32°F
last April 28, first October 12
Median at 28°F
last April 17, first October 22

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 22May 17May 13May 10May 7May 4May 1Apr 28Apr 23
32°FMay 13May 8May 4May 1Apr 28Apr 25Apr 22Apr 18Apr 14
28°FMay 2Apr 28Apr 24Apr 20Apr 17Apr 14Apr 11Apr 8Apr 4
24°FApr 22Apr 17Apr 12Apr 8Apr 6Apr 4Apr 2Mar 30Mar 23
20°FApr 10Apr 5Apr 3Mar 31Mar 29Mar 26Mar 22Mar 17Mar 11
16°FApr 1Mar 29Mar 25Mar 20Mar 17Mar 14Mar 11Mar 7Mar 2

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 19Sep 24Sep 28Sep 30Oct 2Oct 5Oct 7Oct 10Oct 14
32°FSep 29Oct 3Oct 7Oct 9Oct 12Oct 15Oct 17Oct 20Oct 25
28°FOct 8Oct 14Oct 17Oct 20Oct 22Oct 24Oct 27Oct 29Nov 1
24°FOct 19Oct 23Oct 26Oct 28Oct 31Nov 2Nov 4Nov 7Nov 12
20°FOct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 20Nov 25
16°FNov 4Nov 8Nov 12Nov 16Nov 19Nov 22Nov 26Dec 1Dec 6

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°F166160155152147143139135128
32°F184179174170166161157152144
28°F205198194189186182178173166
24°F228220215211207203199193187
20°F248241236231226222218214207
16°F270261255250245241237232224

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
6,384
Cooling degree days, base 65°F
918
Growing degree days, base 40°F
5,434
Growing degree days, base 45°F
4,292
Growing degree days, base 50°F
3,266
Growing degree days, base 55°F
2,355
Growing degree days, base 60°F
1,569

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,35600
February1,09602
March833231
April43410131
May16664372
June21200628
July3294756
August8234691
September97101458
October39214170
November789026
December1,18902

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 22.1 km from Lisbon. 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 USC00131319 (Cedar Rapids #1). Public domain.