Our own count, from NOAA and Census records
Rockford summer heat data: how hard a Rockford air conditioner works now
The airport weather station south of Rockford has logged a high and low nearly every day since 1951. Counting through 75 complete years of it, the 2016-2025 stretch averaged 18.8 afternoons at 90°F or above and 54.1 at 85°F or above, up from 14.8 and 44 over 1991-2020.
Rockford airport: afternoons that hit 90°F, counted each year
Rockford nights that never fell below 70°F, by year
Eight things the record shows
- Ninety is more common. From 14.8 a year (1991-2020) to 18.8 (2016-2025), and 21.5 a year across the first 6 full years of the 2020s.
- Eighty-five is the everyday summer now. 54.1 such afternoons a year recently, against 44 in the older baseline. Call it seven or eight weeks of a condenser running most of the afternoon.
- Nights hold their heat. Lows of 70°F or warmer rose from 8.9 nights a year to 12.8; lows of 65°F or warmer, from 34.7 to 44.4.
- It zigzags. The 1950s managed 21.6 ninety degree days a year, and 1988 and 2012 tower over every recent summer. The climb since the 2000s is plain, yet any one year can buck it.
- The window widened. Recently the first 85°F afternoon has come near May 17 and the last near September 27, about 133 days apart. The 1991-2020 window was May 16 to September 19.
- July carries the load. Roughly 16 afternoons at 85°F or above in July, 14 in June, 11 in August, and still 7 in September.
- The extremes. Top reading since 1951: 105°F, July 7, 2012. Longest unbroken stretch of 85 degree highs: 27 days, through July 23, 2012. Warmest overnight low: 80°F, July 19, 2019.
- This year. 17 ninety degree days by October 24, 2026; the 1991-2020 pace for that date was 14.8. Peak so far 96°F (July 27, 2026), and 17 nights that stayed at 70°F or warmer.
Which months bring Rockford's 85 degree afternoons
Rockford's year in temperature: typical afternoon high over typical overnight low
Ten years at a time
| Years | 90°F+ afternoons, yearly mean | 85°F+ afternoons, yearly mean | 70°F+ nights, yearly mean |
|---|---|---|---|
| 1950s | 21.6 | 50.7 | 8.8 |
| 1960s | 11.6 | 35.5 | 5.0 |
| 1970s | 13.4 | 43.8 | 8.9 |
| 1980s | 18.3 | 46.3 | 11.5 |
| 1990s | 12.3 | 39.1 | 7.5 |
| 2000s | 13.1 | 40.9 | 6.6 |
| 2010s | 17.8 | 49.1 | 12.0 |
| 2020 to 2025 | 21.5 | 57.2 | 13.7 |
The housing stock, ZIP by ZIP
Why put house age next to weather? Because the age of a house predicts the kind of cooling job it is. Pre-war houses tend to have narrow ducts or radiators and none at all. Houses from the 1990s on mostly came with central air that is now due for repair or replacement. And the gas heat column shows how many homes already have a furnace or boiler a heat pump could split the heating with.
| ZIP | Area | Housing units | Median year built | Built before 1940 | Built 2000 or later | Owner occupied | Gas heat |
|---|---|---|---|---|---|---|---|
| 61107 | East Side (northeast) | 13,854 | 1964 | 17% | 9% | 71% | 86% |
| 61008 | Belvidere | 13,378 | 1978 | 19% | 23% | 77% | 81% |
| 61108 | East Side (East State) | 12,751 | 1968 | 6% | 5% | 65% | 83% |
| 61109 | South Rockford / airport | 11,846 | 1974 | 7% | 12% | 64% | 87% |
| 61103 | North End / Edgewater | 11,032 | 1955 | 30% | 3% | 52% | 81% |
| 61111 | Loves Park | 10,574 | 1985 | 6% | 26% | 60% | 81% |
| 61104 | Southeast / Midtown | 9,101 | 1939 or earlier | 56% | 5% | 38% | 79% |
| 61115 | Machesney Park | 9,004 | 1978 | 3% | 18% | 80% | 91% |
| 61101 | Northwest Rockford | 8,714 | 1960 | 23% | 9% | 51% | 83% |
| 61073 | Roscoe | 7,587 | 1993 | 2% | 34% | 80% | 90% |
| 61102 | Southwest Rockford | 7,064 | 1956 | 24% | 11% | 64% | 89% |
| 61114 | Far east side / Perryville | 6,735 | 1982 | 1% | 9% | 71% | 82% |
| 61080 | South Beloit | 5,040 | 1985 | 12% | 26% | 73% | 79% |
| 61072 | Rockton | 4,374 | 1990 | 7% | 31% | 84% | 79% |
| 61065 | Poplar Grove | 3,729 | 1996 | 9% | 38% | 93% | 82% |
| 61088 | Winnebago | 2,378 | 1986 | 14% | 28% | 90% | 74% |
| 61016 | Cherry Valley | 2,325 | 1990 | 9% | 31% | 90% | 91% |
| 61063 | Pecatonica | 1,765 | 1961 | 34% | 13% | 78% | 61% |
| 61024 | Durand | 1,096 | 1971 | 26% | 10% | 81% | 56% |
The area label is our shorthand for the biggest neighborhood or town in that ZIP. Figures are Census ACS 2020-2024 5-year estimates from tables B25034, B25035, B25003 and B25040. When a ZIP's median year built falls in the oldest bucket, the Census reports it as "1939 or earlier". Sort by clicking any column heading.
About these numbers
How many 90 degree days does Rockford get a year?
Recently about 18.8: that is the 2016-2025 mean at the airport station, with 54.1 afternoons a year reaching 85°F. For comparison, 1991-2020 came out at 14.8 and 44.
What is the hottest temperature recorded at the Rockford airport?
105°F, on July 7, 2012, is the top value in the daily data we pulled, which starts in 1951. Runner-up: 104°F on August 16, 1988.
Method
Weather. We downloaded NOAA NCEI's Global Historical Climatology Network daily file for station USW00094822, Chicago Rockford International Airport, covering January 1, 1951 through October 24, 2026. A year stays in only if it has both a high and a low on at least 355 days, leaving 75 full years (1951-2025). Days where the recorded low exceeded the high, a typical data-entry slip, were screened out; there were 0. Our "baseline" is the 1991-2020 mean and "recent" is 2016-2025. NOAA publishes its own official normals; these counts are ours.
Housing. American Community Survey 2020-2024 5-year estimates from the Census Bureau, by ZIP Code Tabulation Area, pulled through Census Reporter. When we say "city" we mean the 8 ZIPs that sit mostly within Rockford; the boundaries don't line up perfectly, and 61114 and 61109 both extend beyond city limits.
Caveats. A single station at the airport, out in open land south of town, can't speak for every block. A tree-shaded street by the Rock River may run a little cooler on a July afternoon, and a paved commercial strip a little warmer. The Census also doesn't ask which homes have air conditioning. Read this as a picture of the area, never as a diagnosis of your own equipment.
Reuse. Reporters and home inspectors may cite or republish the charts and tables under CC BY 4.0, with a link back here.