Monrovia climate

Monrovia Weather in September

NOAA 1991-2020 normals for Martinsville 2 Sw, 19.6 km from Monrovia

Average highs run from 82°F on September 1 to 73°F on September 30, and lows from 58°F to 47°F. Normal precipitation for the month is 3.52 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 Monrovia, 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
53°F
Precipitation
3.52 in
Record high
97°FSep 2, 2011
Record low
37°FSep 24, 2012
Chance of a freeze
6%
Days of 90°F or more
1.8
Daylight
13 h 03 min to 11 h 49 min
Cloud cover
48%
Humidity
70%
Dew point
55°F
Wind
6.9 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°F58°F96°F 201152°F 200924%0%
Sep 282°F58°F97°F 201153°F 200924%0%
Sep 382°F58°F97°F 201153°F 202423%0%
Sep 481°F57°F96°F 202645°F 199723%0%
Sep 581°F57°F94°F 200747°F 199723%0%
Sep 681°F57°F93°F 199849°F 201123%0%
Sep 781°F56°F93°F 200248°F 201723%0%
Sep 880°F56°F94°F 200245°F 202423%0%
Sep 980°F56°F93°F 200247°F 202423%0%
Sep 1080°F55°F95°F 201348°F 199923%0%
Sep 1179°F55°F92°F 201350°F 201723%0%
Sep 1279°F55°F91°F 201951°F 199723%0%
Sep 1379°F54°F89°F 199847°F 201423%0%
Sep 1479°F54°F90°F 199845°F 199623%0%
Sep 1578°F53°F93°F 202644°F 200723%0%
Sep 1678°F53°F92°F 202643°F 201124%0%
Sep 1778°F53°F91°F 202646°F 201424%0%
Sep 1877°F52°F91°F 201847°F 199924%0%
Sep 1977°F52°F91°F 202441°F 201224%0%
Sep 2076°F51°F91°F 201845°F 200324%0%
Sep 2176°F51°F94°F 202442°F 200624%0%
Sep 2276°F50°F94°F 201741°F 199925%0%
Sep 2375°F50°F92°F 201043°F 199925%0%
Sep 2475°F50°F91°F 200737°F 201225%0%
Sep 2575°F49°F91°F 201742°F 200125%0%
Sep 2674°F49°F91°F 201742°F 200025%0%
Sep 2774°F48°F89°F 199842°F 200025%0%
Sep 2873°F48°F89°F 199944°F 202226%0%
Sep 2973°F47°F89°F 202542°F 200026%0%
Sep 3073°F47°F90°F 201939°F 200326%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Monrovia, 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 (EDT).

September 1
sunrise 7:14 AM, sunset 8:17 PM
September 30
sunrise 7:41 AM, sunset 7:30 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00125407 (Martinsville 2 Sw), public domain. Records: NOAA GHCN-Daily, station USW00053842, 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.