Union County climate

Union County Weather in September

NOAA 1991-2020 normals for Grenville, 18.2 km from Union County

Average highs run from 82°F on September 1 to 73°F on September 30, and lows from 54°F to 44°F. Normal precipitation for the month is 1.77 in over about 5 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 Union County, in °F, with the record for each date.20406080100151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
78°F
Average low
50°F
Precipitation
1.77 in
Record high
99°FSep 3, 1947
Record low
26°FSep 29, 1985
Chance of a freeze
18%
Days of 90°F or more
1.6
Daylight
12 h 57 min to 11 h 51 min
Cloud cover
39%
Humidity
51%
Dew point
43°F
Wind
10.7 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 182°F54°F97°F 192247°F 191521%0%
Sep 282°F54°F97°F 194743°F 193421%0%
Sep 381°F54°F99°F 194737°F 196120%0%
Sep 481°F54°F97°F 198333°F 196120%0%
Sep 581°F53°F99°F 194841°F 196120%0%
Sep 681°F53°F99°F 202041°F 189819%0%
Sep 781°F53°F98°F 202340°F 191819%0%
Sep 880°F53°F94°F 191433°F 202019%0%
Sep 980°F52°F96°F 202132°F 202018%0%
Sep 1080°F52°F98°F 202134°F 189818%0%
Sep 1180°F52°F99°F 202135°F 202018%0%
Sep 1279°F51°F95°F 202136°F 198917%0%
Sep 1379°F51°F95°F 201037°F 198917%0%
Sep 1479°F51°F97°F 195636°F 198917%0%
Sep 1579°F50°F96°F 189836°F 194716%0%
Sep 1678°F50°F94°F 200034°F 195116%0%
Sep 1778°F50°F95°F 200032°F 197116%0%
Sep 1878°F49°F94°F 199732°F 197116%0%
Sep 1977°F49°F94°F 198333°F 197115%0%
Sep 2077°F48°F92°F 195632°F 191815%0%
Sep 2177°F48°F92°F 192629°F 198315%0%
Sep 2276°F48°F94°F 189834°F 197014%0%
Sep 2376°F47°F94°F 189834°F 197014%0%
Sep 2476°F47°F92°F 199835°F 192614%0%
Sep 2575°F46°F94°F 202031°F 192613%0%
Sep 2675°F46°F94°F 202029°F 192613%0%
Sep 2775°F46°F94°F 200928°F 192713%0%
Sep 2874°F45°F91°F 189828°F 194513%0%
Sep 2974°F45°F94°F 201026°F 198512%0%
Sep 3073°F44°F91°F 192828°F 198412%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Union 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 6:25 AM, sunset 7:22 PM
September 30
sunrise 6:48 AM, sunset 6:39 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00293706 (Grenville), public domain. Records: NOAA GHCN-Daily, station USW00023051, 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.