Paris climate

Paris Frost Dates and Growing Season

NOAA 1991-2020 normals for Bern, 12.1 km from Paris, elevation 5964 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bern. 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 17 and the first fall freeze around September 3, a growing season of about 77 days.

Median at 32°F
last June 17, first September 3
Median at 28°F
last May 25, first September 16

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 4Jun 30Jun 25Jun 21Jun 17Jun 14Jun 9Jun 5May 31
28°FJun 17Jun 9Jun 3May 30May 25May 21May 18May 14May 9
24°FMay 26May 18May 14May 10May 7May 4May 1Apr 28Apr 23
20°FMay 7May 2Apr 28Apr 25Apr 21Apr 18Apr 15Apr 12Apr 6
16°FApr 23Apr 17Apr 13Apr 9Apr 6Apr 4Apr 1Mar 29Mar 21

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 18Aug 24Aug 29Sep 1Sep 3Sep 6Sep 10Sep 13Sep 18
28°FSep 1Sep 5Sep 9Sep 13Sep 16Sep 19Sep 23Sep 27Oct 1
24°FSep 10Sep 17Sep 22Sep 26Sep 29Oct 2Oct 5Oct 10Oct 15
20°FSep 26Oct 1Oct 4Oct 7Oct 11Oct 15Oct 19Oct 22Oct 26
16°FOct 6Oct 13Oct 18Oct 21Oct 24Oct 26Oct 30Nov 2Nov 7

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°F706459555045413629
32°F1029286817772676153
28°F135127121116111106999384
24°F164157152146142137132126118
20°F193187181176171167162157147
16°F221213208203198194190183176

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
8,825
Cooling degree days, base 65°F
139
Growing degree days, base 40°F
3,088
Growing degree days, base 45°F
2,202
Growing degree days, base 50°F
1,463
Growing degree days, base 55°F
867
Growing degree days, base 60°F
420

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,46600
February1,25200
March1,07900
April74609
May487081
June23810241
July5972478
August7652443
September3054188
October688023
November1,03200
December1,39800

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 12.1 km from Paris. 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 USC00100803 (Bern). Public domain.