511
CXUS55 KRIW 012021
CLMCPR
CLIMATE REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
212 PM MDT WED OCT 01 2025
...PRELIMINARY MONTHLY CLIMATE SUMMARY FOR CASPER FOR THE MONTH OF
SEPTEMBER 2025...
...OFFICIAL CLIMATE DATA FOR THE MONTH OF SEPTEMBER 2025 WILL BE
AVAILABLE IN APPROXIMATELY 60 DAYS FROM THE NATIONAL CENTERS FOR
ENVIRONMENTAL INFORMATION (HTTP://WWW.NCDC.NOAA.GOV/CDO-
WEB/DATASETS). UNOFFICIAL ASOS DAILY SUMMARIES ARE AVAILABLE ON THE
INTERNET AT HTTP://WWW.WEATHER.GOV/CLIMATE/INDEX.PHP?WFO=RIW
..SEPTEMBER WAS WETTER AND WARMER THAN NORMAL FOR CASPER
AVERAGE TEMPERATURE FOR CASPER IN SEPTEMBER WAS 61.5 DEGREES WHICH
IS 2.6 DEGREE ABOVE NORMAL. THE WARMEST READING OF THE MONTH WAS 90
DEGREES ON THE 10TH. THE COLDEST READING FOR THE MONTH WAS 32
DEGREES ON THE 6TH AND BROKE THE 1956 RECORD OF 33.
TOTAL PRECIPITATION FOR THE MONTH WAS 2.55 INCHES...WHICH IS 268
PERCENT OF NORMAL. IT WAS THE 6TH WETTEST SEPTEMBER SINCE RECORDS
BEGAN IN 1939. THE WETTEST 24-HOUR PERIOD DURING THE MONTH WAS ON
THE 16TH-17TH WITH 2.05 INCHES. THE 16H HAD 1.24 INCHES AND BROKE
THE 2006 RECORD OF 1.24 INCHES. THE 17TH HAD 0.82 INCHES AND BROKE
THE 2003 RECORD OF 0.75. THE 23RD HAD 0.38 INCHES AND BROKE 0.29
FROM 1961 AND 2000. THE HIGHEST WIND GUST WAS 67 MPH FROM THE SOUTH
ON THE 11TH.
..THE CASPER WY CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 2025
CLIMATE NORMAL PERIOD: 1991 TO 2020
CLIMATE RECORD PERIOD: 1939 TO 2025
WEATHER OBSERVED NORMAL DEPART LAST YEAR'S
VALUE DATE(S) VALUE FROM VALUE
NORMAL
..........................................................
TEMPERATURE (F)
RECORD
HIGH 100 09/04/2022
LOW 15 09/28/1945
HIGHEST 90 09/10
LOWEST 32 09/06
AVG. MAXIMUM 77.5 75.6 1.9
AVG. MINIMUM 45.4 42.2 3.2
MEAN 61.5 58.9 2.6
DAYS MAX >= 90 1
DAYS MAX <= 32 0
DAYS MIN <= 32 1
DAYS MIN <= 0 0
PRECIPITATION (INCHES)
RECORD
MAXIMUM 3.40 1982
MINIMUM 0.07 1956
TOTALS 2.55 0.95 1.60 0.24
DAILY AVG. 0.09 0.03 0.06
DAYS >= .01 6
DAYS >= .10 3
DAYS >= .50 2
DAYS >= 1.00 1
GREATEST
24 HR. TOTAL 2.05 09/16 TO 09/17
STORM TOTAL 1.24
SNOWFALL (INCHES)
TOTALS 0.0 1.5 -1.5
SINCE 7/1 0.0 1.5 -1.5
SNOWDEPTH AVG. 0
DAYS >= 1.0 0
DEGREE DAYS
HEATING TOTAL 113 214 -101
SINCE 7/1 123 258 -135
COOLING TOTAL 17 30 -13
SINCE 1/1 467 442 25
..........................................................
WIND (MPH)
AVERAGE WIND SPEED 8.8
RESULTANT WIND SPEED/DIRECTION 4/240
HIGHEST WIND SPEED/DIRECTION 44/220 DATE 09/11
HIGHEST GUST SPEED/DIRECTION 67/190 DATE 09/11
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM
AVERAGE SKY COVER 0.20
NUMBER OF DAYS FAIR 26
NUMBER OF DAYS PC 2
NUMBER OF DAYS CLOUDY 2
AVERAGE RH (PERCENT) 54
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 7 MIXED PRECIP 0
HEAVY RAIN 2 RAIN 3
LIGHT RAIN 13 FREEZING RAIN 0
LT FREEZING RAIN 0 HAIL 0
HEAVY SNOW 0 SNOW 0
LIGHT SNOW 0 SLEET 0
FOG 4 FOG W/VIS <= 1/4 MILE 1
HAZE 9
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.
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