First and last freeze/frost dates for Casper, WY ,United States

First and last freeze/frost dates for:
  Your results  
Each winter, on average, your risk of frost is from
September 19 through May 22.

Almost certainly, however, you will receive frost from September 29 through May 5.

You are almost guaranteed that you will not get frost from June 8 through September 10.

Your frost-free growing season is around 120 days.

Detailed station data* follows:

Casper Wb Ap, WY (Natrona county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° Jun 8 Jun 2 May 29 May 25 May 22 May 18 May 15 May 11 May 5
Spring 28° May 18 May 14 May 10 May 7 May 5 May 2 Apr 29 Apr 26 Apr 21
Spring 24° May 9 May 4 May 1 Apr 28 Apr 25 Apr 23 Apr 20 Apr 16 Apr 12
Fall 32° Sep 10 Sep 13 Sep 15 Sep 17 Sep 19 Sep 21 Sep 23 Sep 25 Sep 29
Fall 28° Sep 15 Sep 20 Sep 23 Sep 26 Sep 28 Oct 1 Oct 4 Oct 7 Oct 12
Fall 24° Sep 26 Oct 1 Oct 5 Oct 8 Oct 11 Oct 15 Oct 18 Oct 22 Oct 27

Bates Creek 2, WY (Natrona county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° Jun 19 Jun 12 Jun 7 Jun 3 May 30 May 25 May 21 May 16 May 9
Spring 28° May 24 May 18 May 14 May 10 May 7 May 3 Apr 30 Apr 26 Apr 20
Spring 24° May 7 May 3 Apr 29 Apr 26 Apr 24 Apr 21 Apr 18 Apr 15 Apr 10
Fall 32° Sep 12 Sep 15 Sep 17 Sep 19 Sep 21 Sep 23 Sep 25 Sep 27 Sep 30
Fall 28° Sep 15 Sep 19 Sep 22 Sep 25 Sep 27 Sep 30 Oct 2 Oct 5 Oct 9
Fall 24° Sep 24 Sep 29 Oct 3 Oct 7 Oct 10 Oct 13 Oct 17 Oct 21 Oct 26

Powder River 2 Sw, WY (Natrona county):

Temperature10%20%30%40%50%60%70%80%90%
Spring 32° Jun 18 Jun 12 Jun 7 Jun 3 May 30 May 26 May 22 May 17 May 11
Spring 28° May 28 May 23 May 20 May 17 May 15 May 12 May 10 May 6 May 2
Spring 24° May 16 May 10 May 7 May 3 Apr 30 Apr 27 Apr 24 Apr 20 Apr 15
Fall 32° Aug 29 Sep 3 Sep 7 Sep 10 Sep 13 Sep 16 Sep 19 Sep 23 Sep 28
Fall 28° Sep 5 Sep 10 Sep 14 Sep 17 Sep 20 Sep 23 Sep 27 Sep 30 Oct 6
Fall 24° Sep 14 Sep 20 Sep 24 Sep 28 Oct 2 Oct 5 Oct 9 Oct 14 Oct 20

* This station data is available courtesy the National Climatic Data Center.

For each weather station, you will see a temperature along with tables of data organized into percentage columns. The percentage column tells you the probability that you will experience that row's temperature on or near that date. Here are two examples to help you determine your probable last frost and first freeze dates.

Example 1 (Last Frost). In the Spring 32° row, if you have "Apr 15" under the 50% column, that means you have a 50% chance of seeing frost on or before April 15th.

Example 2 (First Freeze). In the Fall 24° row, if you have "Dec 1" under the 90% column, that means you have a 90% chance of seeing 24 degrees on or after December 1st.

Empty cells indicate you have a less than 10% chance of ever seeing that temperature.

BACK TO TOP