Ennis climate

Ennis Frost Dates and Growing Season

NOAA 1991-2020 normals for Ennis, 1.8 km from Ennis, elevation 4953 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ennis. 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 June 16 and the first fall freeze around September 4, a growing season of about 78 days.

Median at 32°F
last June 16, first September 4
Median at 28°F
last May 23, first September 18

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°F–––––––––
32°FJul 6Jun 29Jun 23Jun 20Jun 16Jun 12Jun 8Jun 4May 30
28°FJun 12Jun 4May 30May 26May 23May 20May 17May 13May 9
24°FMay 22May 17May 13May 11May 8May 6May 3Apr 30Apr 24
20°FMay 12May 8May 4May 1Apr 28Apr 24Apr 19Apr 16Apr 10
16°FMay 2Apr 25Apr 20Apr 16Apr 11Apr 8Apr 5Apr 1Mar 25

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°F–––––––––
32°FAug 20Aug 25Aug 30Sep 1Sep 4Sep 6Sep 8Sep 13Sep 19
28°FSep 1Sep 6Sep 11Sep 14Sep 18Sep 21Sep 24Sep 28Oct 2
24°FSep 15Sep 22Sep 25Sep 28Oct 1Oct 3Oct 6Oct 11Oct 16
20°FSep 28Oct 2Oct 5Oct 9Oct 12Oct 16Oct 20Oct 24Oct 29
16°FOct 5Oct 14Oct 18Oct 21Oct 25Oct 28Oct 31Nov 3Nov 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°F706256514743383328
32°F1039488837874696353
28°F1351291231191141101059989
24°F164157151147143139135129122
20°F194185178173168163158153146
16°F218210204199193187182176167

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
8,190
Cooling degree days, base 65°F
102
Growing degree days, base 40°F
3,093
Growing degree days, base 45°F
2,151
Growing degree days, base 50°F
1,385
Growing degree days, base 55°F
783
Growing degree days, base 60°F
352

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25400
February1,08600
March96002
April717015
May484188
June2587218
July7952439
August10337401
September3165180
October673038
November98604
December1,27600

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 1.8 km from Ennis. 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 USC00242793 (Ennis). Public domain.