Original analysis of NOAA and Census data

Stockton heat data: how hard summer is on an air conditioner

Stockton now averages 29.2 days a year at 100°F or hotter, up from 18.9 in 1991-2020, based on 76 years of daily readings at Stockton Metropolitan Airport. 2024 set the record with 49. The nights have barely changed, and that is the part of the story most people miss.

Every day of 2026 so far, colored by the afternoon high at Stockton Metropolitan Airport. 60 days reached 95°F and 19 reached 100°F through October 24, 2026.under 6060s, 70s75 to 8485 to 9495 to 99100 to 104105+NOAA NCEI daily summaries, station USW00023237.

Days per year at 100°F or hotter, Stockton Metropolitan Airport

Source: NOAA NCEI daily summaries, station USW00023237, 1949-2025 (years with gaps left out). 2026 runs through October 24, 2026.

Days per year at 95°F or hotter

Source: NOAA NCEI daily summaries, station USW00023237, 1970 to October 24, 2026. A 95 degree afternoon is when most older systems start running without a break.

What we found

More 100 degree days. 18.9 a year in 1991-2020, 29.2 in 2016-2025, and 30.3 a year so far in the 2020s (6 complete years). Days at 95°F or more went from 48.3 to 61.3.
A record in 2024. 2024 had 49 days at 100°F or hotter, the most of any complete year since 1949. The next highest years are in the table below.
Nights still cool off. Nights with a low of 65°F or more went from 13.8 a year to 18.8, a small change next to the afternoons. In July the high and low are now about 36 degrees apart (34 in 1991-2020). An air conditioner here gets a break most nights, which is why a system that never catches up overnight is worth a look.
A longer season. Over 2016-2025 the first 100°F day came around June 2 on average and the last around September 13. In 1991-2020 it was June 11 to September 10. The 95 degree season now runs from about May 22 to October 2.
Peak months: July averages about 20 days at 95°F or more and August about 17. June averages 12 and September 8.
Records: the hottest reading since 1949 was 115°F, on July 23, 2006 and again on September 6, 2022. The longest run of 100°F days was 14 in a row, ending August 2, 1980. The warmest night had a low of 82°F, on July 23, 2006, during the same heat wave.
2026 so far: 19 days at 100°F or more through October 24, 2026, against a 1991-2020 average of 18.9 by that date, and 60 days at 95°F or more against 48.3. The high for the year was 106°F on September 10, 2026.
Dry summers: 81% of the airport's average yearly rain (13.43 inches, 1991-2020) falls from November through March. Summer air is dry, so outdoor coils collect dust and farm debris instead of getting rinsed.

Average days at 95°F or hotter, by month

Source: NOAA NCEI daily summaries, station USW00023237, 2016-2025 average.

Average daily high and low by month, Stockton Metropolitan Airport

Top number is the average high, bottom is the average low, 2016-2025. The gap between them is the valley's night cooling. Source: NOAA NCEI daily summaries, station USW00023237.

A dirt track through a dry summer field under a cloudless blue sky — A dry valley summer, here near the American River in the Sacramento area. Stockton gets almost no rain from June through September. Photo: Cathy Poland / Unsplash

By decade

Decade	Days at 100°F+ per year	Days at 95°F+ per year	Nights at 65°F+ per year
1950s	14.2	39.4	9.4
1960s	20.1	49.7	16.5
1970s	23.4	51.0	20.9
1980s	20.4	45.1	16.2
1990s	14.8	40.9	18.4
2000s	21.3	51.2	10.3
2010s	19.2	49.2	12.9
2020 to 2025	30.3	61.3	19.2

Decades with fewer than 7 complete years are left out. The 1950s row covers 9 years because 1951 has gaps.

Homes by ZIP code

Older housing tends to mean older ducts and systems that were added or replaced piecemeal. Heating fuel shows which homes already rely on electric heat, where a heat pump is the usual replacement.

ZIP	Area	Housing units	Median year built	Built before 1980	Built 2000 or later	Owner occupied	Electric heat
95207	Lincoln Village / Venetian Gardens	20,339	1972	75%	3%	42%	39%
95206	South Stockton / Weston Ranch	18,787	1994	35%	34%	60%	34%
95376	Tracy (central)	17,699	1985	38%	11%	62%	24%
95240	Lodi (east and central)	17,354	1971	64%	14%	51%	27%
95336	Manteca (north)	17,154	1984	42%	29%	71%	23%
95337	Manteca (south)	14,536	2004	15%	60%	74%	27%
95209	Spanos Park / North Stockton	14,106	1986	37%	30%	74%	33%
95210	Northeast Stockton / Hammer Lane	12,509	1982	45%	9%	51%	37%
95204	Central Stockton / Miracle Mile	12,344	1955	90%	4%	59%	31%
95219	Brookside / Lincoln Village West	12,023	1990	26%	30%	61%	34%
95205	East Stockton / Wilson Way	11,707	1963	71%	13%	50%	36%
95242	Lodi (west)	11,441	1983	44%	25%	70%	26%
95377	Tracy (south)	10,584	2004	4%	73%	75%	22%
95330	Lathrop	9,202	2007	11%	68%	85%	24%
95212	Morada / Northeast	8,357	2003	25%	65%	78%	23%
95391	Mountain House	7,412	2011	8%	90%	70%	24%
95215	East of Stockton / Waterloo	7,276	1965	69%	14%	59%	24%
95366	Ripon	6,970	1991	34%	40%	66%	27%
95203	West of downtown / Fremont Park	5,754	1955	76%	10%	43%	34%
95304	Tracy (north and rural)	5,410	1999	28%	49%	60%	33%
95320	Escalon	5,037	1986	39%	22%	71%	21%
95202	Downtown Stockton	4,071	1938	84%	4%	9%	47%
95220	Acampo	2,840	1979	51%	21%	71%	25%
95236	Linden	1,881	1980	49%	17%	59%	28%
95258	Woodbridge	1,648	1985	30%	5%	84%	25%
95237	Lockeford	1,529	1982	46%	6%	75%	27%
95231	French Camp	647	1974	57%	25%	58%	28%

Area names are our shorthand for the main neighborhood or town in each ZIP. Census ACS 2020-2024 5-year estimates (tables B25034, B25035, B25003, B25040). Click a column to sort.

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How we built this

Temperature. NOAA NCEI Global Historical Climatology Network daily summaries for Stockton Metropolitan Airport (station USW00023237), October 1, 1948 to October 24, 2026, pulled October 29, 2026. A year counts only if it has a high and low on at least 355 days, which leaves 76 complete years between 1949 and 2025. "Normal" here means the average of 1991-2020; "recent" means 2016-2025. These are our own counts from the daily record, not NOAA's official normals.

Homes. US Census American Community Survey 2020-2024 5-year estimates by ZIP Code Tabulation Area, via Census Reporter, pulled October 29, 2026.

Limits. One airport station doesn't describe every neighborhood. Tracy and Mountain House sit closer to the Altamont Pass winds, and Lodi and Ripon sit a little higher. Use this to understand the area, not to diagnose your system.

Using this data. Feel free to quote or republish this data under CC BY 4.0, with a link to this page.