Ventura climate

Ventura Frost Dates and Growing Season

NOAA 1991-2020 normals for Mason City Muni AP, 12.7 km from Ventura, elevation 1225 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mason City Muni AP. 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 3 and the first fall freeze around October 1, a growing season of about 150 days.

Median at 36°F
last May 11, first September 24
Median at 32°F
last May 3, first October 1
Median at 28°F
last April 24, first October 11

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 25May 20May 17May 14May 11May 9May 6May 4Apr 30
32°FMay 15May 10May 7May 5May 3Apr 30Apr 28Apr 24Apr 19
28°FMay 7May 3Apr 30Apr 27Apr 24Apr 21Apr 17Apr 13Apr 9
24°FApr 29Apr 23Apr 20Apr 15Apr 13Apr 10Apr 8Apr 4Mar 30
20°FApr 21Apr 14Apr 10Apr 7Apr 4Apr 2Mar 30Mar 25Mar 19
16°FApr 11Apr 5Apr 2Mar 30Mar 27Mar 22Mar 19Mar 14Mar 9

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 10Sep 15Sep 18Sep 20Sep 24Sep 26Sep 29Oct 1Oct 5
32°FSep 18Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 10Oct 15
28°FSep 27Oct 1Oct 4Oct 7Oct 11Oct 13Oct 16Oct 20Oct 23
24°FOct 7Oct 13Oct 17Oct 20Oct 22Oct 24Oct 27Oct 30Nov 3
20°FOct 19Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 15
16°FOct 30Nov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 19Nov 25

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°F150145140137134130126122116
32°F168162157153150146143138131
28°F187181177172169165161156149
24°F208201196193189185182176170
20°F229221216212208204201195189
16°F250242236232227222218213206

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
7,647
Cooling degree days, base 65°F
603
Growing degree days, base 40°F
4,578
Growing degree days, base 45°F
3,547
Growing degree days, base 50°F
2,628
Growing degree days, base 55°F
1,825
Growing degree days, base 60°F
1,145

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,52800
February1,26100
March997013
April573367
May24635278
June39142554
July10212666
August26147586
September16457355
October5256100
November932010
December1,34500

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 12.7 km from Ventura. 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 USW00014940 (Mason City Muni AP). Public domain.