812
CXUS55 KRIW 012024
CLMP60
CLIMATE REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
212 PM MDT WED OCT 01 2025
...PRELIMINARY MONTHLY CLIMATE SUMMARY FOR LAKE YELLOWSTONE FOR THE
MONTH OF SEPTEMBER 2025...
...OFFICIAL CLIMATE DATA FOR THE MONTH OF SEPTEMBER 2025 WILL BE
AVAILABLE APPROXIMATELY IN 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
..LAKE YELLOWSTONE WAS WARMER AND DRIER THAN NORMAL IN SEPTEMBER
AVERAGE TEMPERATURE FOR LAKE YELLOWSTONE IN SEPTEMBER WAS 48.6
DEGREES WHICH IS 3.2 DEGREES ABOVE NORMAL. IT WAS THE 5TH WARMEST
SEPTEMBER SINCE RECORDS BEGAN IN 1998. THE WARMEST READING OF THE
MONTH WAS 78 DEGREES ON THE 3RD. THE HIGH OF 69 ON THE 20TH TIED
WITH 2012. THE COLDEST READING OF THE MONTH WAS 27 DEGREES ON THE
23RD.
TOTAL PRECIPITATION AT LAKE YELLOWSTONE WAS 1.46 INCHES...WHICH WAS
93 PERCENT OF NORMAL. THE WETTEST 24-HOUR PERIOD DURING THE MONTH
WAS THE 7TH WHEN 0.76 INCHES OF PRECIPITATION FELL. THIS BROKE THE
2002 RECORD OF 0.49. THE HIGHEST WIND GUST WAS 30 MPH FROM THE WEST
ON THE 7TH.
...THE LAKE YELLOWSTONE WY CLIMATE SUMMARY FOR THE MONTH OF
SEPTEMBER 2025...
CLIMATE NORMAL PERIOD: 1991 TO 2020
CLIMATE RECORD PERIOD: 1998 TO 2025
WEATHER OBSERVED NORMAL DEPART LAST YEAR'S
VALUE DATE(S) VALUE FROM VALUE
NORMAL
..........................................................
TEMPERATURE (F)
RECORD
HIGH 83 09/07/2022
LOW 13 09/24/2000
HIGHEST 78 09/03
LOWEST 27 09/23
AVG. MAXIMUM 64.6 60.5 4.1
AVG. MINIMUM 32.5 30.3 2.2
MEAN 48.5 45.4 3.1
DAYS MAX >= 90 0
DAYS MAX <= 32 0
DAYS MIN <= 32 16
DAYS MIN <= 0 0
PRECIPITATION (INCHES)
RECORD
MAXIMUM 4.09 2013
MINIMUM 0.21 2018
TOTALS 1.46 1.57 -0.11 1.43
DAILY AVG. 0.05 0.05 -0.00
DAYS >= .01 11
DAYS >= .10 3
DAYS >= .50 1
DAYS >= 1.00 0
GREATEST
24 HR. TOTAL 0.76 09/07 TO 09/07
STORM TOTAL 0.76
DEGREE DAYS
HEATING TOTAL 484 588 -104
SINCE 7/1 1000 1230 -230
COOLING TOTAL 0 0 0
SINCE 1/1 1 0 1
..........................................................
WIND (MPH)
AVERAGE WIND SPEED 1.9
RESULTANT WIND SPEED/DIRECTION 0/080
HIGHEST WIND SPEED/DIRECTION 17/270 DATE 09/07
17/280 09/11
HIGHEST GUST SPEED/DIRECTION 30/270 DATE 09/07
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM
AVERAGE SKY COVER 0.00
NUMBER OF DAYS FAIR 28
NUMBER OF DAYS PC 0
NUMBER OF DAYS CLOUDY 0
AVERAGE RH (PERCENT) 63
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 1 MIXED PRECIP 0
HEAVY RAIN 1 RAIN 1
LIGHT RAIN 11 FREEZING RAIN 0
LT FREEZING RAIN 0 HAIL 0
HEAVY SNOW 0 SNOW 0
LIGHT SNOW 0 SLEET 0
FOG 0 FOG W/VIS <= 1/4 MILE 0
HAZE 0
- INDICATES NEGATIVE NUMBERS.
R INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T INDICATES TRACE AMOUNT.
LOOKING AHEAD TO OCTOBER 2025. THE AVERAGE HIGH TEMPERATURE ON THE
FIRST OF THE MONTH IS 53 DEGREES...AND THE AVERAGE LOW TEMPERATURE
IS 27 DEGREES. THE AVERAGE HIGH BY THE END OF THE MONTH IS 39
DEGREES AND THE AVERAGE LOW TEMPERATURE IS 17 DEGREES. THE AVERAGE
MONTHLY PRECIPITATION IS 1.85 INCHES.
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