September
September · August · June
81climate match
United States · 1991–2020
Best time to visit
Rock Falls.
September leads for comfortable weather in Rock Falls: typically 24°C by day, 11.5°C at night, with 99 mm of rain. Based on measured 1991–2020 NOAA station history.
Best comfortSeptember
Typical high24°C
Typical low11.5°C
Rain in September99 mm
July
July · August · June
67climate match
May
May · October · September
70climate match
The weakest month is January, scoring 5 against September’s 81 — days reach only -1.5°C, 25° below the 24°C the score treats as ideal.
Month by month
The whole year,
without the guesswork.
The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.
Jan
5-1.5° / -10.6°
Feb
51.3° / -8.4°
Mar
98.3° / -2.4°
Apr
3615.4° / 3.2°
May
6321.6° / 9.7°
Jun
7026.5° / 15.2°
Jul
6827.9° / 17.1°
Aug
7327.2° / 16.1°
Sep
8124° / 11.5°
Oct
4917° / 5°
Nov
138.6° / -1.3°
Dec
51.7° / -6.9°
| Month | Day | Night | Rain | Wet days | Daylight | Comfort | Coverage |
|---|---|---|---|---|---|---|---|
| January | -1.5°C | -10.6°C | 48 mm | 6.8 | 9 h 27 | 5 | Good coverage |
| February | 1.3°C | -8.4°C | 49 mm | 5.9 | 10 h 31 | 5 | Strong coverage |
| March | 8.3°C | -2.4°C | 69 mm | 6.7 | 11 h 48 | 9 | Strong coverage |
| April | 15.4°C | 3.2°C | 97 mm | 9.1 | 13 h 17 | 36 | Strong coverage |
| May | 21.6°C | 9.7°C | 127 mm | 10.4 | 14 h 31 | 63 | Good coverage |
| June | 26.5°C | 15.2°C | 148 mm | 9.2 | 15 h 12 | 70 | Strong coverage |
| July | 27.9°C | 17.1°C | 112 mm | 7.6 | 14 h 56 | 68 | Strong coverage |
| August | 27.2°C | 16.1°C | 112 mm | 7.6 | 13 h 51 | 73 | Strong coverage |
| September | 24°C | 11.5°C | 99 mm | 6.7 | 12 h 26 | 81 | Strong coverage |
| October | 17°C | 5°C | 78 mm | 6.8 | 11 h 00 | 49 | Strong coverage |
| November | 8.6°C | -1.3°C | 64 mm | 6.6 | 9 h 46 | 13 | Strong coverage |
| December | 1.7°C | -6.9°C | 53 mm | 6.9 | 9 h 09 | 5 | Strong coverage |
What has changed
Rock Falls runs +0.4°C
on the 1961–1990 baseline.
Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.
Jan
+0.8
Feb
+0.8
Mar
+1.9
Apr
-0.8
May
-0.1
Jun
+0.1
Jul
-1.2
Aug
-0.7
Sep
+1.1
Oct
+0.2
Nov
+0.2
Dec
+2.7
| Month | Record high | Record low | Wettest day | Wettest / driest month | Years |
|---|---|---|---|---|---|
| January | 18.3°C3 Jan 2004 | -35.6°C17 Jan 2009 | 48 mm24 Jan 1938 | 103 mm1974 · driest 5 mm in 1981 | 125 |
| February | 24.4°C28 Feb 2024 | -32.8°C13 Feb 1905 | 46 mm20 Feb 1994 | 139 mm2019 · driest 0 mm in 1969 | 129 |
| March | 30.6°C30 Mar 1986 | -25.0°C4 Mar 2002 | 56 mm5 Mar 1976 | 142 mm1920 · driest 5 mm in 1910 | 130 |
| April | 33.9°C26 Apr 1986 | -13.3°C7 Apr 1982 | 67 mm17 Apr 2006 | 223 mm1973 · driest 9 mm in 1901 | 129 |
| May | 40.6°C31 May 1934 | -4.4°C3 May 2005 | 124 mm17 May 1974 | 285 mm1996 · driest 12 mm in 1934 | 129 |
| June | 41.1°C1 Jun 1934 | 1.1°C6 Jun 1894 | 126 mm19 Jun 2014 | 289 mm1993 · driest 6 mm in 1988 | 130 |
| July | 43.3°C14 Jul 1936 | 6.1°C23 Jul 1904 | 129 mm10 Jul 1922 | 298 mm2025 · driest 4 mm in 1894 | 129 |
| August | 39.4°C3 Aug 1930 | 2.8°C29 Aug 1934 | 114 mm18 Aug 2016 | 320 mm2016 · driest 8 mm in 2003 | 129 |
| September | 38.9°C15 Sep 1939 | -5.6°C28 Sep 1942 | 126 mm1 Sep 1989 | 296 mm1970 · driest 1 mm in 1979 | 129 |
| October | 35.0°C1 Oct 1897 | -13.9°C28 Oct 1925 | 119 mm11 Oct 1931 | 241 mm1954 · driest 0 mm in 2011 | 131 |
| November | 27.2°C1 Nov 1933 | -22.2°C26 Nov 1977 | 74 mm3 Nov 1935 | 192 mm1935 · driest 1 mm in 1904 | 131 |
| December | 20.0°C5 Dec 1998 | -31.7°C24 Dec 1983 | 79 mm10 Dec 2003 | 159 mm2008 · driest 0 mm in 2017 | 128 |
| Month | Days 25°C+ | Days 30°C+ | Frost nights | Heavy rain (10 mm+) | Snow days |
|---|---|---|---|---|---|
| January | 0 | 0 | 29 | 2 | 6 |
| February | 0 | 0 | 26 | 2 | 3 |
| March | <1 | 0 | 22 | 3 | 2 |
| April | 3 | <1 | 8 | 3 | <1 |
| May | 10 | 2 | <1 | 4 | 0 |
| June | 21 | 7 | 0 | 4 | 0 |
| July | 26 | 9 | 0 | 4 | 0 |
| August | 24 | 7 | 0 | 4 | 0 |
| September | 14 | 4 | <1 | 3 | 0 |
| October | 4 | <1 | 6 | 2 | <1 |
| November | <1 | 0 | 19 | 2 | 1 |
| December | 0 | 0 | 27 | 2 | 4 |
| Month | Warm & dry days | Wet days | Washouts | Week with 3+ wet days | Daytime mean has ranged |
|---|---|---|---|---|---|
| January | 0% | 20% | 4% | 18% | -5.5–2.5°C |
| February | <1% | 19% | 4% | 15% | -3.0–5.2°C |
| March | 5% | 24% | 7% | 25% | 4.6–11.4°C |
| April | 21% | 30% | 10% | 36% | 12.7–18.9°C |
| May | 48% | 32% | 11% | 39% | 19.8–25.2°C |
| June | 69% | 29% | 12% | 33% | 24.8–29.6°C |
| July | 76% | 24% | 10% | 25% | 27.0–32.1°C |
| August | 75% | 24% | 10% | 23% | 26.1–31.0°C |
| September | 64% | 24% | 10% | 25% | 22.4–27.1°C |
| October | 33% | 21% | 7% | 21% | 15.0–21.2°C |
| November | 4% | 22% | 7% | 20% | 5.6–11.7°C |
| December | <1% | 20% | 5% | 17% | -2.1–4.9°C |
A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.
The evidence behind this page
Nearby, measured,
and named.
- Place identity
- GeoNames 4907898
- NOAA station
- USC00112348 · DIXON WWTP
- Station distance
- 15.8 km from the place centre
- Climate period
- 1991–2020
- Minimum month coverage
- 24 usable years
- Daylight
- Calculated from latitude 41.78°, mid-month, sunrise to sunset including refraction. Not a station measurement.
- Important limit
- Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.