Western and Central Wyoming

Weather Forecast Office

Casper 2021 Annual Summary

...Highlights of 2021...

Annual:
- 26th warmest year on record at 46.3 degrees, just 0.7 degrees above normal.
- 17th wettest year with 14.52 inches, 119% of normal.
- 7th snowiest year with 108.1 inches, 151% of normal.
- Highest wind gust was 90 mph on March 29th.
Monthly Temperatures: 2nd coldest February on record. 4th warmest June (tie), 4th warmest November and 8th warmest December on record.
Monthly Precipitation: 1st wettest March, 8th driest May and 4th wettest October on record.
Monthly Snowfall: 1st snowiest March and 4th snowiest October on record.

Temperature

Precipitation

Snow

Winds

Temperature Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Average High	34.0	42.7	48.7	58.5	64.6	85.4	90.00	88.4	82.4	68.2	45.7	45.3	62.8
Mean High (1991-2020 Normals)	35.2	37.8	48.8	56.3	66.8	79.6	89	86.7	75.6	59.7	45.9	34.7	59.7
Average Low	10.7	20.6	23.3	28.7	35.0	47.3	50.3	51.5	44.2	31.8	23.6	21.6	32.4
Mean Low (1991-2020 Normals)	15	15.4	22.7	28.2	37.1	45.4	53	51.4	42.2	30.9	22	14.8	31.5
Average Temperature	22.3	31.7	36.0	43.6	49.8	66.3	70.1	70.0	63.3	50.0	34.7	33.4	47.6
Mean Average Temperature (1991-2020 Normals)	25.1	26.6	35.8	42.3	52	62.5	71	69	58.9	45.3	34	24.8	45.6
Departure from Normal	-2.8	5.1	0.2	1.3	-2.2	3.8	-0.9	1.0	4.4	4.7	0.7	8.6	2.0
Rank: 85 years of record (P.O.R 12/1939-2024)	32	74	55	52	20	73	28	53	81	70	54	84	80

Highest Daily Maximum	56	60	63	75	86	98	100	99	94	85	62	57	100
Date of Occurrence	31	6	18	12,13,14	29	23	11,25	3,6	2	2,4	11,12	21	6/11,25
Lowest Daily Minimum	-37	-16	13	18	19	36	39	34	30	21	3	8	-37
Date of Occurrence	13	16	25	21	2	1	8	30	14,22	23	24	31	1/13
Number of Days with:	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Maximum >= 90°	0	0	0	0	0	7	16	6	0	0	0	0	43
Maximum <= 32°	12	5	1	0	0	0	0	0	0	0	1	2	21
Minimum <= 32°	28	27	28	19	8	0	0	0	3	18	25	30	186
Minimum <= 0°	8	2	0	0	0	0	0	0	0	0	0	0	10
Record High Temperatures Set or Tied	1	0	0	1	0	0	1	2	1	1	1	3	11
Record Low Temperatures Set or Tied	0	0	0	0	1	1	0	2	0	0	0	0	4

Temperature Ranks and Records:

Daily Records:

Record High Temperatures:

  January: 53 on the 29th (tie)

April: 75 on the 12th (tie)

July: 100 on the 25th

August: 99 on the 3rd. 96 on the 21st.

September: 91 on the 29th (also the latest 90 degree day on record)

October: 85 on the 4th

November: 60 on the 23rd (tie)

December: 56 on the 20th (tie). 57 on the 21st. 51 on the 29th (tie)

Record Low Temperatures:

  May: 23 on the 4th
June: 37 on the 29th

August: 36 on the 29th. 34 on the 30th (tie)

Warmest Months of September on Record
Rank	Year	Average Temperature °F
1	1998	64.7
2	2015	64.4
3	1940	64.3
4	1963	64.1
5	2024	63.3
6	1969,1990,1952	63.2
9	1948	63.1
10	1994	62.8

Warmest Months of December on Record
Rank	Year	Average Temperature °F
1	1980	34.3
2	2024	33.4
3	1946	33.0
4	2023	32.0
5	1957/1994	31.8
6	1950	31.2
7	1962	30.4
8	1959	30.3
9	2021	30.1
10	1999	29.9

Top Ten Warmest Years on Record
Rank	Year	Average Temperature °F
1	1994	49.1
2	2012	48.7
3	1954	48.3
4	1981	48.1
5	1992	48.0
6	2024	47.6
7	1940, 1953, 1963	47.3
10	2015, 2006, 1999	47.1

Top Ten Coldest Years on Record
Rank	Year	Average Temperature °F
1	1985	42.5
2	1951	43.1
3	1978	43.2
4	1964	43.5
5	2019, 1975	43.6
6	2009, 1979, 1968, 1949	43.8
11	1971	43.9
80	2024	47.6


Average Annual Temperature for Period of Record - Click on Graph to Enlarge

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Precipitation Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Total (inches)	0.36	0.67	0.57	1.22	2.44	0.80	0.53	0.39	0.24	1.51	0.39	0.16	9.28
Mean Precipitation (1991-2020 Normals)	0.49	0.56	0.84	1.41	2.21	1.34	1.19	0.79	0.95	1.19	0.64	0.61	12.22
Departure from Normal	-0.13	0.11	-0.27	-0.19	0.23	-0.54	-0.66	-0.4	-0.71	0.32	-0.25	-0.45	-2.94
Percent of Normal	73	120	68	87	110	60	45	49	25	127	61	26	76
Rank - 85 years (P.O.R 12/1939-2024)	27	58	29	38	54	32	18	32	14	70	24	8	15

Greatest 24-HR Total	0.15	0.20	0.25	0.83	0.54	0.48	0.15	0.2	0.14	0.94	0.27	0.12	0.94
Dates of Occurrence	11	15-16	13	6	15	7-8	19	25-26	3-4	29-30	24	29-30	10/29-30
Number of Days with:
Precipitation >= 0.01	7	8	7	9	8	7	11	4	4	6	3	4	78
Precipitation >= 0.10	1	3	3	2	7	2	1	2	0	4	2	1	28
Precipitation >= 1.00	0	0	0	0	0	0	0	0	0	1	0	0	0
Days with Thunderstorms	0	0	0	2	2	5	9	7	3	1	1	0	30
Daily Precipitation Records Set or Tied	0	0	0	0	0	0	0	0	0	1	0	0	1

Precipitation Ranks and Records:

One Day Precipitation Records:

October: 0.85" on the 29th.

Top Ten Driest December's on Record
Rank	Year	Precipitation (inches)
1	1952	0.03
2	2023	0.06
3	2004	0.07
4	1998/1999	0.10
6	2001	0.13
7	1969/2024	0.16
8	2002	0.19
9	1974	0.22
10	1958/1962	0.23

Top Ten Driest Years on Record
Rank	Year	Precipitation (inches)
1	2020	5.79
2	1988	6.56
3	2001	6.76
4	2002	7.05
5	1960	7.34
6	1954	7.70
7	2012	7.88
8	1963	7.90
9	1966	8.14
10	1943	8.91
15	2024	9.28

Top Ten Wettest Years on Record
Rank	Year	Precipitation (inches)
1	1982	20.48
2	1995	18.94
3	1983	18.41
4	1978	17.64
5	1941	16.24
6	1957	16.12
7	1986	15.92
8	1993	15.91
9	2009	15.77
10	2016	15.57
71	2024	9.28


Annual Precipitation for Period of Record - Click on Graph to Enlarge

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Snow Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Total (inches)	6.5	8.8	2.7	6.6	3.9	0	0	0	0	*11	*4.9	1.5	45.9
Mean Snowfall (1991-2020 Normals)	9	10.9	10.3	10.5	2.6	0.1	0	0	1.5	7	8.9	11	71.8
Departure from Normal	-2.5	-2.1	-7.6	-3.9	1.3	-0.1	0.0	0.0	-1.5	4	-4	-9.5	-25.9
Percent of Normal	72	81	26	63	150	0	0	0	0	157	55	14	64
Rank - Least to Most 85 years (P.O.R 12/1939-2024)	27	39	4	31	62	NA	NA	NA	NA	68	25	3	6

Greatest 24-HR Total	2.1	2.9	1.2	4.8	3.9	0	0	0	0	11	3	1.5	11
Dates of Occurrence	11	16	25	6	3	NA	NA	NA	NA	30	25	30	10/30
Number of Days with:
Snowfall >= 1.0 inch	2	4	1	1	1	0	0	0	0	1	2	1	13
Daily Snowfall Records Set or Tied	0	0	0	0	0	0	0	0	0	0	0	0	0
* October and November snowfall estimated due to no official observer. Note: 50 months of September on record with no snowfall.

Snowfall Ranks and Records:

March had 4th least snowfall on record

December had 3rd least snowfall on record

One Day Snowfall Records (inches):

There were no daily snowfall records set in 2024.

Top Ten Snowiest Years on Record
Rank	Year	Snowfall (inches)
1	1982	137.6
2	1975	124.0
3	1984	121.2
4	1973	118.3
5	2023	116.1
6	1983	114.2
7	1978	112.7
8	2021	108.1
9	2013	107.5
10	1955	103.3
80	2024	45.9



Annual and Seasonal Snowfall for Period of Record - Click on Graph to Enlarge

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Wind Banner

Element	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Average Speed (MPH)	12.8	14.9	13.1	10.7	10.9	11.5	8.7	9.9	10.1	9.8	13	14.8	11.7
Maximum 3-sec Gust	53	62	59	47	53	59	57	58	60	46	60	61	62
Direction	210	240	210	220	260/280	240	20	240	210	210	220	210	240
Date of Occurrence	9	26	2	5	17/29	24	6	25	18	27	13	8	2/26
Number of Days with:
2-Min Wind >50 mph	0	0	0	0	0	0	0	0	0	0	0	0	0
Peak Wind >50 mph	1	4	2	0	4	6	4	3	3	0	3	6	36
Peak Wind >70 mph	0	0	0	0	0	0	0	0	0	0	0	0	0

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