Climatological Report (Monthly)
Issued by NWS
Issued by NWS
039
CXUS55 KRIW 011713 RRA
CLMCPR
CLIMATE REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
1105 AM MDT THU OCT 01 2026
...PRELIMINARY MONTHLY CLIMATE SUMMARY FOR CASPER FOR THE MONTH OF
SEPTEMBER 2026...
...OFFICIAL CLIMATE DATA FOR THE MONTH OF SEPTEMBER 2026 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
...CASPER WAS WARMER AND DRIER THAN NORMAL IN SEPTEMBER...
AVERAGE TEMPERATURE FOR CASPER IN SEPTEMBER WAS 62.7 DEGREES WHICH
IS 3.8 DEGREES ABOVE NORMAL. THE WARMEST READING OF THE MONTH WAS 91
DEGREES ON THE 5TH AND 6TH. THE COLDEST READING WAS 36 DEGREES ON
THE 9TH, 15TH AND 30TH. NO TEMPERATURE RECORDS WERE BROKEN THIS
MONTH.
TOTAL PRECIPITATION FOR THE MONTH WAS 0.76 INCHES...WHICH IS 80
PERCENT OF NORMAL. THE WETTEST 24-HOUR PERIOD DURING THE MONTH WAS
ON THE 13TH WITH 0.35 INCHES. NO PRECIPITATION RECORDS WERE BROKEN
THIS MONTH. THE HIGHEST WIND GUST WAS 60 MPH FROM THE SOUTHWEST ON
THE 2ND. THERE WAS ALSO A GUST TO 59 MPH ON THE 14TH FROM THE
SOUTHWEST.
...THE CASPER WY CLIMATE SUMMARY FOR THE MONTH OF SEPTEMBER 2026...
CLIMATE NORMAL PERIOD: 1991 TO 2020
CLIMATE RECORD PERIOD: 1939 TO 2026
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 91 09/05
09/06
LOWEST 36 09/09
09/15
09/30
AVG. MAXIMUM 79.5 75.6 3.9
AVG. MINIMUM 45.9 42.2 3.7
MEAN 62.7 58.9 3.8
DAYS MAX >= 90 3
DAYS MAX <= 32 0
DAYS MIN <= 32 0
DAYS MIN <= 0 0
PRECIPITATION (INCHES)
RECORD
MAXIMUM 3.40 1982
MINIMUM 0.07 1956
TOTALS 0.76 0.95 -0.19 2.55
DAILY AVG. 0.03 0.03 -0.00
DAYS >= .01 6
DAYS >= .10 2
DAYS >= .50 0
DAYS >= 1.00 0
GREATEST
24 HR. TOTAL 0.35 09/13 TO 09/13
STORM TOTAL 0.35
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 108 214 -106
SINCE 7/1 113 258 -145
COOLING TOTAL 45 30 15
SINCE 1/1 638 442 196
..............................................................
WIND (MPH)
AVERAGE WIND SPEED 10.1
RESULTANT WIND SPEED/DIRECTION 5/240
HIGHEST WIND SPEED/DIRECTION 44/220 DATE 09/02
HIGHEST GUST SPEED/DIRECTION 60/220 DATE 09/02
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM
AVERAGE SKY COVER 0.16
NUMBER OF DAYS FAIR 25
NUMBER OF DAYS PC 4
NUMBER OF DAYS CLOUDY 1
AVERAGE RH (PERCENT) 51
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 5 MIXED PRECIP 0
HEAVY RAIN 0 RAIN 2
LIGHT RAIN 12 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 4
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.
LOOKING AHEAD TO OCTOBER 2026. THE AVERAGE HIGH TEMPERATURE ON THE
FIRST OF THE MONTH IS 67 DEGREES...AND THE AVERAGE LOW TEMPERATURE
IS 36 DEGREES. THE AVERAGE HIGH BY THE END OF THE MONTH IS 53
DEGREES...AND THE AVERAGE LOW TEMPERATURE IS 26. THE AVERAGE MONTHLY
PRECIPITATION IS 1.19 INCHES. THE AVERAGE SNOWFALL IS 7 INCHES.
$$