Summer 2026 was the fourth warmest at Philadelphia's airport since 1941, with three straight days above 100°F

Thu, 15 Oct 2026 08:37:33 -0400

June, July and August 2026 averaged 78.8°F at Philadelphia International Airport, the fourth warmest summer of the 86 in NOAA’s record there since 1941. Only 2010, 2022 and 2016 ran warmer. The average is the mean of each day’s high and low, taken from the station’s daily record through August 31 with no days missing. The summer also brought 34 days at 90°F or hotter, against an average of 25.8 in the summers of 1991 to 2020, and three days in a row above 100°F, from July 2 to July 4.

Summers at the airport have brought more 90-degree days since the 1960s, and 2026 had 34

Days with a high of 90°F or hotter, June through August, Philadelphia International Airport, 1941 to 2026. The line is the trailing 10-summer average.

Counted by Conshy Roofers from NOAA daily highs through ACIS. Source: data.rcc-acis.org

Philadelphia International Airport, the last 12 summers, June through August. Warm nights have a low of 75°F or warmer. The average temperature is the mean of the daily highs and lows.
Summer	Days at 90°F or hotter	Days at 95°F or hotter	Days at 100°F or hotter	Hottest reading (°F)	Nights at 75°F or warmer	Average temperature (°F)
2026	34	8	3	103	15	78.80
2025	36	8	1	101	23	77.39
2024	30	14	0	98	17	78.49
2023	17	2	0	95	6	75.88
2022	43	9	0	99	26	79.33
2021	34	6	0	97	12	77.74
2020	36	7	0	97	15	78.39
2019	30	5	0	98	15	77.59
2018	25	6	0	98	10	76.91
2017	21	3	0	96	9	76.41
2016	38	11	0	98	18	78.85
2015	29	4	0	95	13	77.72

Source: data.rcc-acis.org

How the summer ranks

The airport reached 103°F on July 2, 102°F on July 3 and 101°F on July 4. Since 1941, only one summer reading has been higher, 104°F on July 3, 1966, and 103°F has been reached in three other summers: 1995, 2010 and 2011. Four other summers had three or more days at 100°F or hotter. 1957, 1966 and 1993 had three each, and 1988 had five. No summer since 1993 had as many.

The heat was spread across the season. June had 11 days at 90°F or hotter, July 10 and August 13. August had the most 90-degree days but none at 95°F, and July had six of the summer’s eight days at 95°F or hotter. The longest run of 90-degree days lasted seven days, starting June 29. Two more 90-degree days came in September.

Nights stayed warm too. The low held at 75°F or warmer on 15 nights. Summers from 1941 to 1970 averaged 2.4 such nights, and summers from 1991 to 2020 averaged 9.9. On July 3 the low was 82°F.

The count of 90-degree days varies a lot from one summer to the next. 2023 had 17 and 2025 had 36. Averaged by decade, the 1960s had the fewest, 14.6 a summer, and the 2010s had 28.8. The seven summers from 2020 through 2026 have averaged 32.9.

Closer to Conshohocken

The airport sits at an elevation of 7 feet and is about 15 miles from Conshohocken, by the station coordinates ACIS lists. NOAA’s Norristown station, USC00366370, is about 3 miles from the borough at an elevation of 62 feet. It belongs to the Cooperative Observer Program, where an observer reads the thermometer once a day, and ACIS lists its summer 2026 readings as taken at 6 or 7 a.m. Each Norristown day ends that morning, so an afternoon high shows up under the next day’s date.

Norristown had no missing days from June through August. It recorded 18 days at 90°F or hotter, seven at 95°F or hotter and three at 100°F or hotter. Its top reading was 101°F, dated July 3 and July 4, and it recorded 100°F dated July 5. Those match the airport’s July 2 to 4 heat, shifted by the morning reading. Its summer averaged 76.15°F, and six of its nights stayed at 75°F or warmer.

Summer 2026 at the two stations. Norristown's day ends at its morning reading, and the airport's at midnight.
Measure (June to August 2026)	Philadelphia International Airport	Norristown
Days at 90°F or hotter	34	18
Days at 95°F or hotter	8	7
Days at 100°F or hotter	3	3
Hottest reading (°F)	103	101
Nights at 75°F or warmer	15	6
Average temperature (°F)	78.80	76.15
Days missing	0	0

Source: data.rcc-acis.org

What summer heat does to a shingle roof

These figures are air temperatures. A roof in the sun runs much hotter. The U.S. Department of Energy’s 2010 guide to cool roofs says traditional dark roofs can reach 150°F or more in summer sun, and that most dark roofing materials reflect only 5 to 20% of sunlight. Light-colored materials reflect 55 to 90%, by the same guide’s figures.

Under the roof, the Asphalt Roofing Manufacturers Association (ARMA), the shingle makers’ trade group, says a poorly ventilated attic can reach 140°F on a 90°F day. In a 2023 technical bulletin it says heat buildup in an attic may accelerate the aging of asphalt roofing products. Its 2022 article adds that an overheated attic, combined with moisture, can distort shingles and damage the roof deck, the plywood or boards the shingles are nailed to.

Heat also changes how a roof should be installed and repaired. ARMA’s hot-weather bulletin says shingles soften and scuff under foot traffic in hot weather and become more flexible, so rough handling can tear them. It advises installing early on hot, sunny days and working the west- and south-facing slopes in the morning. Most shingles carry a strip of sealant that bonds each course to the one below once the sun heats it, so a new roof seals itself in summer. That same bond makes repairs harder on an older roof in hot weather: ARMA says pulling up sealed shingles may tear them, and suggests waiting until the shingles are cooler or misting them with water first.

What to ask before you sign

Ask how the attic will be vented and how much vent area the roofer is installing. Vent area is measured as net free area, the open space air can pass through once screens and louvers are counted. Section R806.2 of the 2021 International Residential Code, which Conshohocken’s re-roofing addendum cites, sets a minimum of 1/150 of the vented space. It allows 1/300 when 40 to 50% of the vent area sits in the upper part of the attic, within 3 feet of the ridge, with the rest in the bottom third. In the coldest climate zones, 6 through 8, that exception also requires a vapor retarder on the warm side of the ceiling. As an example with round numbers, a 900-square-foot attic floor needs 6 square feet of net free area at 1/150, or 3 square feet at 1/300. ARMA recommends that intake vents at the eaves make up 50 to 60% of the total and exhaust vents near the ridge 40 to 50%, and says intake should never be less than exhaust.

Conshohocken’s addendum asks the applicant whether the space under the roof is vented and whether the owner was told that a lack of adequate venting may void the manufacturer’s warranty. Read that answer before you sign the addendum. The addendum states the venting rule in slightly different terms from the 2021 code text, so if your attic is close to the line, ask the borough’s Licenses and Inspections office at 610-828-1092 which version it applies.

If a repair is scheduled in midsummer, ask when the crew will work and how they will lift sealed shingles. The roofing contract guide covers what the written contract has to include, the permits guide covers the addendum and the borough’s other forms, and the weather guide covers the area’s rain, wind, hail and freeze-thaw.

Caveats

The National Weather Service says daily observations are preliminary until NOAA’s National Centers for Environmental Information finishes quality control, three or more months after they are taken. The July 2 to 4 readings are just over three months old and the August readings about six weeks old, so the counts here could change slightly.

All the figures are air temperatures at two weather stations. They do not measure roof surfaces or attics. ARMA’s statements about aging describe heat in general, and none of the sources used here ties a given number of hot days to a shorter shingle life.