Rockford weather in September: Rockford, Illinois: normal highs, lows, rain and records for September
Rockford in September has a normal high of 75°F and a normal low of 54°F, a daily mean of 64°F, falling from 80°F on the 1st to 70°F by the 30th. Measurable precipitation falls on 8 days in a normal September, 3.62 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 24°C and low of 12°C, 92 mm of precipitation in September.
- NOAA stationRockford Greater Rockford Airport
- Station IDUSW00094822
- Location42.19°N 89.09°W
- Elevation730 ft (223 m)
- From the center5 miles
- Population147,486
- Jan 29° 15°
- Feb 33° 18°
- Mar 47° 28°
- Apr 60° 39°
- May 71° 50°
- Jun 81° 60°
- Jul 84° 64°
- Aug 82° 62°
- Sep 75° 54°
- Oct 62° 42°
- Nov 47° 31°
- Dec 34° 20°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Rockford in September?
The normal high is 75°F and the normal low 54°F, for a daily mean of 64.4°F. September is 7.5°F cooler than August and 12.4°F warmer than October. September is the 4th warmest month of the year in Rockford and the 6th wettest. Across the month the normal high falls 10°F, from 80°F on September 1 to 70°F on September 30. From one year to the next September's mean temperature typically moves about 2.7°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 62°F and 67°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 30%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 80°F | 59°F | 29% | 19% |
| September 8 | 78°F | 57°F | 29% | 19% |
| September 15 | 76°F | 54°F | 29% | 19% |
| September 22 | 73°F | 51°F | 29% | 18% |
| September 30 | 70°F | 48°F | 30% | 17% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 80°F | 59°F | 29% | 19% | 13 h 10 min |
| September 2 | 80°F | 59°F | 29% | 19% | 13 h 10 min |
| September 3 | 79°F | 58°F | 29% | 19% | 13 h 10 min |
| September 4 | 79°F | 58°F | 29% | 19% | 13 h |
| September 5 | 79°F | 58°F | 29% | 19% | 13 h |
| September 6 | 79°F | 57°F | 29% | 19% | 13 h |
| September 7 | 78°F | 57°F | 29% | 19% | 13 h |
| September 8 | 78°F | 57°F | 29% | 19% | 12 h 50 min |
| September 9 | 78°F | 56°F | 29% | 19% | 12 h 50 min |
| September 10 | 77°F | 56°F | 29% | 19% | 12 h 50 min |
| September 11 | 77°F | 55°F | 29% | 19% | 12 h 40 min |
| September 12 | 77°F | 55°F | 29% | 19% | 12 h 40 min |
| September 13 | 77°F | 55°F | 29% | 19% | 12 h 40 min |
| September 14 | 76°F | 54°F | 29% | 19% | 12 h 40 min |
| September 15 | 76°F | 54°F | 29% | 19% | 12 h 30 min |
| September 16 | 75°F | 53°F | 29% | 18% | 12 h 30 min |
| September 17 | 75°F | 53°F | 29% | 18% | 12 h 30 min |
| September 18 | 75°F | 53°F | 29% | 18% | 12 h 20 min |
| September 19 | 74°F | 52°F | 29% | 18% | 12 h 20 min |
| September 20 | 74°F | 52°F | 29% | 18% | 12 h 20 min |
| September 21 | 74°F | 51°F | 29% | 18% | 12 h 20 min |
| September 22 | 73°F | 51°F | 29% | 18% | 12 h 10 min |
| September 23 | 73°F | 51°F | 29% | 18% | 12 h 10 min |
| September 24 | 72°F | 50°F | 29% | 18% | 12 h 10 min |
| September 25 | 72°F | 50°F | 29% | 17% | 12 h 10 min |
| September 26 | 72°F | 49°F | 29% | 17% | 12 h |
| September 27 | 71°F | 49°F | 29% | 17% | 12 h |
| September 28 | 71°F | 48°F | 30% | 17% | 12 h |
| September 29 | 70°F | 48°F | 30% | 17% | 11 h 50 min |
| September 30 | 70°F | 48°F | 30% | 17% | 11 h 50 min |
- Normal high
- 75°FSeptember average
- Normal low
- 54°FSeptember average
- Precipitation
- 3.62 inmonth total
- Days with precipitation
- 80.01 inch or more
- Days at 90°F or more
- 2
- Daylight
- 13 h 10 min to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 23
- Days at 80°F or more
- 11
- Sunshine
- 78%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00094822; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Rockford in September?
On a given September day the chance of 0.01 inch or more is 29% on average, highest around September 29 (30%). In all, 3.62 in falls on 8 days of a normal September, 1 of them with an inch or more.
In a normal September in Rockford, 2 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00094822.
How humid and windy is Rockford in September?
At 3 p.m. the normal temperature is 68°F with 48% relative humidity and a dew point of 47°F; at 6 a.m. it is 50°F with 87% humidity. The wind averages 8.2 mph, most often from the west-southwest in the afternoon. A dew point under 50°F feels dry.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 50°F | 46°F | 87% | 6.0 mph | 37% |
| 9 a.m. | 59°F | 49°F | 69% | 9.7 mph | 45% |
| noon | 66°F | 48°F | 52% | 11.4 mph | 34% |
| 3 p.m. | 68°F | 47°F | 48% | 11.3 mph | 41% |
| 6 p.m. | 61°F | 48°F | 61% | 7.8 mph | 39% |
| 9 p.m. | 56°F | 48°F | 75% | 7.1 mph | 55% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00094822. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in Rockford?
The warmest September temperature on Rockford's official record (since 1893) is 103°F, on September 7, 1939; the coldest is 24°F, on September 28, 1942. The wettest September brought 10.68 in (1961).
The September mean against the 1991-2020 normal of 64.4°F: 2021 68.9°F (+4.5), 2022 64.5°F (+0.1), 2023 67.0°F (+2.6), 2024 67.0°F (+2.6), 2025 66.5°F (+2.1), 2026 68.0°F (+3.6). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 68.9°F | +4.5°F | 0.53 in |
| 2022 | 64.5°F | +0.1°F | 5.84 in |
| 2023 | 67.0°F | +2.6°F | 2.19 in |
| 2024 | 67.0°F | +2.6°F | 2.05 in |
| 2025 | 66.5°F | +2.1°F | 1.05 in |
| 2026 | 68.0°F | +3.6°F | 7.40 in |
Source: records: ACIS, NWS threaded record RFDthr; recent months: ACIS, station USW00094822. Records and recent months use complete months only.
How does September in Rockford compare across Illinois?
Across the 144 places PlainClimate covers in Illinois, September normal highs run from 72°F in Barrington to 84°F in Anna; Rockford's is 75°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.