Petroleum County climate

Petroleum County Weather in September

NOAA 1991-2020 normals for Valentine, 31 km from Petroleum County

Average highs run from 80°F on September 1 to 67°F on September 30, and lows from 47°F to 36°F. Normal precipitation for the month is 1.16 in over about 6 wet days.

September day by day

The normal high and low for each date, and the record, in °F.

Normal daily high and low temperature at Petroleum County, in °F, with the record for each date.020406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
74°F
Average low
42°F
Precipitation
1.16 in
Record high
100°FSep 4, 1950
Record low
15°FSep 30, 1985
Chance of a freeze
85%
Days of 90°F or more
3.1
Daylight
13 h 20 min to 11 h 43 min
Cloud cover
53%
Humidity
48%
Dew point
39°F
Wind
9.4 mph

Every day of the month

A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.

DateNormal highNormal lowRecord highRecord lowChance wetChance of snow
Sep 180°F47°F99°F 198336°F 195419%0%
Sep 279°F46°F99°F 194530°F 191419%0%
Sep 379°F46°F99°F 202228°F 195919%0%
Sep 479°F46°F100°F 195025°F 195619%0%
Sep 578°F45°F98°F 197630°F 195619%0%
Sep 678°F45°F98°F 198026°F 195620%0%
Sep 777°F45°F100°F 202231°F 197220%0%
Sep 877°F44°F98°F 197925°F 194320%0%
Sep 977°F44°F98°F 198123°F 196220%
Sep 1076°F43°F92°F 196828°F 194520%
Sep 1176°F43°F93°F 196621°F 198920%
Sep 1275°F43°F97°F 195320°F 198920%
Sep 1375°F42°F93°F 195926°F 197020%
Sep 1475°F42°F96°F 194818°F 197020%
Sep 1574°F42°F93°F 197926°F 197021%
Sep 1674°F41°F94°F 199825°F 197021%
Sep 1773°F41°F91°F 194325°F 196521%
Sep 1873°F41°F96°F 198119°F 196521%
Sep 1972°F40°F97°F 198122°F 191521%
Sep 2072°F40°F90°F 193826°F 197821%
Sep 2171°F40°F93°F 193617°F 199521%
Sep 2271°F39°F94°F 193822°F 196121%
Sep 2371°F39°F90°F 196622°F 193421%
Sep 2470°F39°F92°F 193821°F 193421%
Sep 2570°F38°F92°F 201519°F 193421%
Sep 2669°F38°F92°F 196318°F 197220%
Sep 2769°F37°F91°F 196320°F 194520%
Sep 2868°F37°F90°F 193819°F 198420%
Sep 2968°F37°F90°F 198918°F 195920%
Sep 3067°F36°F93°F 196315°F 198520%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Petroleum County, in percent, and of at least 0.1 inch of snowfall.05101520251102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (MDT).

September 1
sunrise 6:32 AM, sunset 7:52 PM
September 30
sunrise 7:11 AM, sunset 6:54 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00248498 (Valentine), public domain. Records: NOAA GHCN-Daily, station USC00243727, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-25. Sun and moon: computed with the NOAA solar equations and Meeus.