Helena climate

Helena Weather in September

NOAA 1991-2020 normals for Helena 1 Sse, 0.9 km from Helena

Average highs run from 90°F on September 1 to 80°F on September 30, and lows from 66°F to 55°F. Normal precipitation for the month is 2.56 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 Helena, in °F, with the record for each date.20406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
85°F
Average low
61°F
Precipitation
2.56 in
Record high
109°FSep 1, 1939
Record low
33°FSep 30, 1985
Chance of a freeze
0%
Days of 90°F or more
10.8
Daylight
12 h 57 min to 11 h 50 min
Cloud cover
46%
Humidity
59%
Dew point
56°F
Wind
11.0 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 190°F66°F109°F 193951°F 195622%0%
Sep 290°F65°F108°F 193953°F 191522%0%
Sep 389°F65°F107°F 193948°F 197422%0%
Sep 489°F65°F109°F 200048°F 197422%0%
Sep 589°F64°F107°F 200049°F 196122%0%
Sep 689°F64°F106°F 199849°F 191822%0%
Sep 788°F64°F106°F 199849°F 191821%0%
Sep 888°F64°F104°F 192245°F 195721%0%
Sep 988°F63°F104°F 191247°F 202021%0%
Sep 1087°F63°F104°F 191241°F 196221%0%
Sep 1187°F63°F102°F 191145°F 194021%0%
Sep 1287°F62°F107°F 200043°F 190221%0%
Sep 1386°F62°F109°F 191839°F 190221%0%
Sep 1486°F61°F103°F 202644°F 196121%0%
Sep 1586°F61°F104°F 197841°F 191621%0%
Sep 1685°F61°F103°F 189541°F 191621%0%
Sep 1785°F60°F101°F 189540°F 190321%0%
Sep 1885°F60°F102°F 191042°F 197321%0%
Sep 1984°F60°F104°F 191038°F 191821%0%
Sep 2084°F59°F102°F 194437°F 190121%0%
Sep 2184°F59°F101°F 202439°F 198321%0%
Sep 2283°F58°F100°F 202437°F 199520%0%
Sep 2383°F58°F99°F 193339°F 189520%0%
Sep 2482°F57°F97°F 191135°F 198920%0%
Sep 2582°F57°F101°F 193940°F 191320%0%
Sep 2682°F57°F98°F 190435°F 191220%0%
Sep 2781°F56°F99°F 191137°F 194220%0%
Sep 2881°F56°F106°F 195335°F 190920%0%
Sep 2980°F55°F98°F 191135°F 191620%0%
Sep 3080°F55°F99°F 199833°F 198520%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Helena, 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 (CDT).

September 1
sunrise 7:04 AM, sunset 8:01 PM
September 30
sunrise 7:28 AM, sunset 7:18 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00344019 (Helena 1 Sse), public domain. Records: NOAA GHCN-Daily, station USC00342912, 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 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.