407
CXUS55 KRIW 011716
CLMP60
CLIMATE REPORT
NATIONAL WEATHER SERVICE RIVERTON WY
1105 AM MDT THU OCT 01 2026
...PRELIMINARY MONTHLY CLIMATE SUMMARY FOR LAKE YELLOWSTONE FOR THE
MONTH OF SEPTEMBER 2026...
...OFFICIAL CLIMATE DATA FOR THE MONTH OF SEPTEMBER 2026 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 WETTER THAN NORMAL IN SEPTEMBER
THE AVERAGE TEMPERATURE FOR LAKE YELLOWSTONE IN SEPTEMBER WAS 47.1
DEGREES WHICH IS 1.7 DEGREES ABOVE NORMAL. THE WARMEST READING OF
THE MONTH WAS 72 DEGREES ON THE 6TH. THE COLDEST READING OF THE
MONTH WAS 25 DEGREES ON THE 15TH AND BROKE 26 DEGREES FROM 2003,
2004 AND 2005.
TOTAL PRECIPITATION AT LAKE YELLOWSTONE WAS 1.71 INCHES...WHICH WAS
109 PERCENT OF NORMAL. THE WETTEST 24-HOUR PERIOD DURING THE MONTH
WAS THE 17-18TH WITH 0.84 INCHES. THE 18TH HAD 0.53 INCHES AND TIED
THE 2013 RECORD. THE HIGHEST WIND GUST WAS 33 MPH FROM THE WEST ON
THE 13TH.
...THE LAKE YELLOWSTONE WY CLIMATE SUMMARY FOR THE MONTH OF
SEPTEMBER 2026...
CLIMATE NORMAL PERIOD: 1991 TO 2020
CLIMATE RECORD PERIOD: 1998 TO 2026
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 72 09/06
LOWEST 25 09/15
AVG. MAXIMUM 61.3 60.5 0.8
AVG. MINIMUM 32.9 30.3 2.6
MEAN 47.1 45.4 1.7
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 1.71 1.57 0.14 1.46
DAILY AVG. 0.06 0.05 0.01
DAYS >= .01 11
DAYS >= .10 6
DAYS >= .50 1
DAYS >= 1.00 0
GREATEST
24 HR. TOTAL 0.84 09/17 TO 09/18
STORM TOTAL 0.53
DEGREE DAYS
HEATING TOTAL 507 588 -81
SINCE 7/1 875 1230 -355
COOLING TOTAL 0 0 0
SINCE 1/1 2 0 2
..........................................................
WIND (MPH)
AVERAGE WIND SPEED 2.7
RESULTANT WIND SPEED/DIRECTION 0/270
HIGHEST WIND SPEED/DIRECTION 20/270 DATE 09/13
HIGHEST GUST SPEED/DIRECTION 33/270 DATE 09/13
SKY COVER
POSSIBLE SUNSHINE (PERCENT) MM
AVERAGE SKY COVER 0.00
NUMBER OF DAYS FAIR 30
NUMBER OF DAYS PC 0
NUMBER OF DAYS CLOUDY 0
AVERAGE RH (PERCENT) 65
WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM 0 MIXED PRECIP 0
HEAVY RAIN 0 RAIN 0
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 2026. 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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