Mercer County climate

Mercer County Weather in September

NOAA 1991-2020 normals for Princeton, 2.9 km from Mercer County

Average highs run from 82°F on September 1 to 72°F on September 30, and lows from 59°F to 48°F. Normal precipitation for the month is 3.81 in over about 7 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 Mercer County, in °F, with the record for each date.20406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
77°F
Average low
54°F
Precipitation
3.81 in
Record high
100°FSep 7, 2013
Record low
33°FSep 29, 2003
Chance of a freeze
11%
Days of 90°F or more
2.7
Daylight
13 h 04 min to 11 h 48 min
Cloud cover
46%
Humidity
70%
Dew point
55°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 182°F59°F96°F 202650°F 200926%0%
Sep 281°F59°F97°F 200050°F 202426%0%
Sep 381°F58°F96°F 202651°F 201026%0%
Sep 481°F58°F94°F 202644°F 202526%0%
Sep 581°F58°F95°F 202646°F 200826%0%
Sep 680°F57°F94°F 200244°F 201726%0%
Sep 780°F57°F100°F 201342°F 202526%0%
Sep 880°F56°F97°F 201345°F 200826%0%
Sep 979°F56°F98°F 201342°F 200826%0%
Sep 1079°F56°F96°F 201348°F 199925%0%
Sep 1179°F55°F96°F 200048°F 200725%0%
Sep 1279°F55°F95°F 202540°F 201425%0%
Sep 1378°F55°F95°F 202538°F 201425%0%
Sep 1478°F54°F90°F 201740°F 201125%0%
Sep 1578°F54°F91°F 201736°F 200725%0%
Sep 1677°F53°F91°F 202543°F 199925%0%
Sep 1777°F53°F90°F 200045°F 199925%0%
Sep 1877°F53°F90°F 201841°F 201225%0%
Sep 1976°F52°F90°F 201340°F 200325%0%
Sep 2076°F52°F97°F 202237°F 200625%0%
Sep 2176°F51°F90°F 201735°F 199925%0%
Sep 2275°F51°F90°F 201740°F 201225%0%
Sep 2375°F51°F91°F 201736°F 201225%0%
Sep 2474°F50°F90°F 201739°F 201125%0%
Sep 2574°F50°F88°F 201737°F 200125%0%
Sep 2674°F50°F89°F 202141°F 200025%0%
Sep 2773°F49°F88°F 202141°F 201224%0%
Sep 2873°F49°F89°F 202137°F 202224%0%
Sep 2973°F48°F91°F 200233°F 200324%0%
Sep 3072°F48°F91°F 200239°F 200924%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Mercer County, in percent, and of at least 0.1 inch of snowfall.01020301102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (CDT).

September 1
sunrise 6:42 AM, sunset 7:46 PM
September 30
sunrise 7:10 AM, sunset 6:58 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00236866 (Princeton), public domain. Records: NOAA GHCN-Daily, station USW00094991, 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.