Black roof surface temperature reaches 150 to 185 degrees Fahrenheit (66 to 85 degrees Celsius) at summer peak, per the U.S. EPA’s Reducing Urban Heat Islands compendium, Cool Roofs chapter, because a traditional dark roof reflects only 5 to 15 percent of sunlight and absorbs the other 85 to 95 percent. The same EPA chapter puts standard black asphalt at 165 to 185 degrees Fahrenheit (74 to 85 degrees Celsius) at midday, and 55 to 85 degrees Fahrenheit (31 to 47 degrees Celsius) hotter than the surrounding air. Multiplied across the 20 to 25 percent of urban land that rooftops cover, that heat helps push U.S. city air about 1 to 7 degrees Fahrenheit above outlying areas by day and 2 to 5 degrees Fahrenheit at night, per the EPA’s heat island overview.
By The Roofing Brief Team. Last reviewed: October 2026.
Headline finding: In peer-reviewed modeling, converting a city’s dark roofs to reflective (high-albedo) surfaces cut heat-related deaths by an estimated 5 to 32 percent, depending on the city and scenario. The largest percentage is London, where cool roofs on every roof (albedo 0.85) would have avoided an estimated 249 of 655 to 920 heat deaths in summer 2018, about 32 percent, per Simpson et al. in Nature Cities (October 2024). The largest absolute U.S. figure is New York City, with up to 219 lives saved per decade when urban surface reflectance rises by 0.20, per the Vanos, Kalkstein and Sailor three-city heat-health report for the Global Cool Cities Alliance.
How hot does a dark roof actually get?
A dark roof gets far hotter than a reflective one because color governs solar reflectance (albedo), the share of sunlight a surface bounces back. At noon on a clear U.S. summer day, a flat surface receives about 1,000 watts of sunlight per square meter, per the Lawrence Berkeley National Laboratory (LBNL) Heat Island Group. A roof reflecting 10 percent absorbs about 900 of those watts; a white roof reflecting 80 percent absorbs about 200.
The EPA compendium gives three reference cases for a hot, sunny summer day: a black roof that reflects 5 percent of sunlight and emits more than 90 percent of the heat it absorbs can reach 180 degrees Fahrenheit (82 degrees Celsius); a bare metal roof reaches about 160 degrees Fahrenheit (71 degrees Celsius) because it sheds only about a fourth of the heat it absorbs; and a cool roof peaks near 120 degrees Fahrenheit (49 degrees Celsius). Cool roofs tend to stay within 10 to 20 degrees Fahrenheit (6 to 11 degrees Celsius) of air temperature, versus 55 to 85 degrees Fahrenheit (31 to 47 degrees Celsius) for conventional roofs.
| Roof surface | Solar reflectance | Peak summer surface temperature | Above air temperature | Source |
|---|---|---|---|---|
| Black roof, 5% reflective, high emittance | 0.05 | 180°F (82°C) | 55 to 85°F (31 to 47°C) for conventional roofs | EPA compendium, ch. 4 |
| Standard black asphalt roof, midday | 0.05 to 0.15 (traditional roofing) | 165 to 185°F (74 to 85°C) | 55 to 85°F (31 to 47°C) | EPA compendium, ch. 4 |
| Uncertified asphalt shingle, California code default | 0.08 aged, 0.75 emittance | not stated | not stated | CRRC summary of 2025 California Energy Code, sec. 110.8(i) |
| Bare metal or metallic surface | high reflectance, low emittance | 150 to 165°F (66 to 77°C) | not stated | EPA compendium, ch. 4 |
| Cool-colored dark roof | 0.35 | about 22°F (12°C) cooler than a look-alike roof at 0.10 | not stated | LBNL Heat Island Group |
| Cool roof, high reflectance and emittance | more than 0.65 new | 110 to 120°F (43 to 49°C) | 10 to 20°F (6 to 11°C) | EPA compendium, ch. 4 |
| Clean white roof | 0.80 | about 55°F (31°C) cooler than a gray roof at 0.20 | not stated | LBNL Heat Island Group |
Peak values vary with slope, ventilation, wind, soiling and cloud cover. Celsius values are the EPA’s own conversions.
Is a black roof 60 to 80 degrees Celsius in summer sun?
Yes, and the top of that range understates it. The EPA compendium gives 66 to 85 degrees Celsius (150 to 185 degrees Fahrenheit) for traditional U.S. roofs at summer peak and 74 to 85 degrees Celsius for standard black asphalt at midday, so a black roof in full sun commonly runs above 80 degrees Celsius. An infrared image in the same EPA chapter shows a traditional bitumen roof in Arizona at almost 80 degrees Celsius (175 degrees Fahrenheit). Readings near 60 degrees Celsius fit milder air temperatures, partial cloud, or a roof that has not yet reached its afternoon peak.
Which roofs must be reflective? Code thresholds by roof type
Cool-roof rules are written as minimum aged solar reflectance, thermal emittance and Solar Reflectance Index (SRI), measured under the Cool Roof Rating Council (CRRC) program. California’s 2025 Energy Code, effective January 1, 2026, sets the strictest residential numbers, summarized in the CRRC chart of 2025 California cool roof requirements. Commercial roofs elsewhere follow IECC 2021 section C402.3 where a jurisdiction has adopted it.
| If your roof is… | Minimum 3-year aged solar reflectance | Minimum thermal emittance | Or minimum SRI | What it means for a black roof |
|---|---|---|---|---|
| California single-family re-roof, steep slope, climate zones 4 and 8 to 15 (sec. 150.2(b)1Ii) | 0.20 | 0.75 | 16 | A plain black shingle at the 0.08 code default fails; use a CRRC-rated cool-colored shingle or claim an exception such as R-38 ceiling insulation or an attic radiant barrier |
| California single-family new build, steep slope, zones 10 to 15 (sec. 150.1(c)11A) | 0.20 | 0.75 | 16 | Same as above |
| California single-family re-roof, low slope, zones 4 and 6 to 15 (sec. 150.2(b)1Iii) | 0.63 | 0.75 | 75 | Effectively a white or near-white membrane or coating |
| California nonresidential, low slope, all zones (sec. 140.3(a)1Aia) | 0.63 | 0.75 | 75 | Dark membranes need the U-factor trade-off exception |
| Commercial low-slope roof, IECC 2021 climate zones 0 to 3 (C402.3) | 0.55 | 0.75 | 64 | Dark membranes do not comply without an exception |
| Roof assembly weighing 25 lb per sq ft or more, such as most tile (California exceptions) | exempt | exempt | exempt | Heavy assemblies are exempt from the reflectance minimums |
| Outside these codes, any climate zone | no minimum | no minimum | no minimum | Color is your choice; check HOA rules and local amendments |
Code sections are as listed by the CRRC chart dated December 4, 2025; read the Energy Code text for the full exception wording before relying on one. For product-by-product SRI values, see our roofing solar reflectance index (SRI) table.
How roof color feeds the urban heat island
Roof color scales into a city-wide effect because rooftops are one of the largest surfaces in the built environment. LBNL analyses for the EPA’s Urban Heat Island Pilot Project, using 1998 to 2002 data, found roofs account for 20 to 25 percent of land cover in four U.S. pilot cities (EPA compendium, ch. 4). The three-city report cites Akbari et al. (2009) for roofs and pavements making up 60 to 70 percent of urban surfaces, with roofs at 20 to 30 percent and pavement at 30 to 45 percent.
The measured result is the urban heat island: U.S. cities average about 1 to 7 degrees Fahrenheit warmer than outlying areas during the day and 2 to 5 degrees Fahrenheit warmer at night, with humid eastern cities and denser, larger cities showing the biggest gaps (EPA heat island overview). On a warm day, conventional roofing can reach as much as 66 degrees Fahrenheit above surrounding air temperature, per the same EPA page.
Roof albedo is also a lever comparable to vegetation. In a Baltimore-Washington heat-wave simulation for 7 to 10 June 2008, Li, Bou-Zeid and Oppenheimer found that green roofs with relatively abundant soil moisture cut surface and near-surface heat islands about as much as cool roofs with an albedo of 0.7 (Environmental Research Letters 9, 055002, 2014). The three-city report adds a practical scale: converting dark gray roofs (reflectance 0.15) to white roofs (0.55) on about 25 percent of a city’s buildings raises city-wide roof reflectivity by 10 percentage points, which normal 20-year roof turnover could deliver in about five years.
The heat-death connection
Extreme heat is a rising cause of U.S. deaths. Death certificates in CDC WONDER recorded 21,518 heat-related deaths from 1999 through 2023, rising from 1,159 in 2020 to a provisional 2,325 in 2023, the highest of the 25-year period, per Howard et al., “Trends of Heat-Related Deaths in the US, 1999-2023” (JAMA, 2024). In 2023 the CDC’s ESSENCE system logged 119,605 emergency department visits for heat-related illness, 92 percent of them between May and September (CDC MMWR, Vaidyanathan et al., 2024).
The burden is uneven. Black Americans are 52 percent more likely than average, and Hispanic Americans 21 percent more likely, to live where heat-related health risk is high, per Jesdale et al. (2013) as cited in the three-city report. Those neighborhoods tend to have older building stock, less tree cover and fewer air-conditioned homes, which is where dark roofs and public health overlap.
Ranked: modeled heat-mortality reduction from reflective roofs
Peer-reviewed and agency-funded urban-albedo studies put the modeled cut in heat-related deaths from raising roof or surface reflectance at 5 to 32 percent, ranked by city below. These are modeled estimates under specific heat scenarios, not observed death counts, and most assume wide or full roof conversion.
| City / region | Modeled heat-death reduction | Scenario | Source |
|---|---|---|---|
| London, UK | ~32% (249 of an estimated 655 to 920 deaths) | Cool roofs (albedo 0.85) on all roofs, summer 2018; mean air temperature change of minus 0.8°C | Simpson et al., Nature Cities (2024) |
| Brussels, Belgium | up to ~25.5% of heat deaths | Cool roofs, July 2019 heat wave | Serras et al., Environment International (2025) |
| West Midlands, UK | ~25% of heat-island-linked heat mortality during a heat wave; 18% over the 2006 summer (7% of total heat mortality) | Cool roofs (albedo 0.7) across the city; summer 2006 plus 2003 and 2006 heat waves | Macintyre and Heaviside, Environment International (2019) |
| Los Angeles, CA | 21% (up to 22 lives per decade) | Urban surface reflectance raised by 0.20 (0.15 to 0.35) | Vanos, Kalkstein, Sailor et al., three-city report |
| New York, NY | 10% (up to 219 lives per decade) | Urban surface reflectance raised by 0.20 | Vanos, Kalkstein, Sailor et al., three-city report |
| Baltimore, MD | 5% (up to 32 lives per decade) | Urban surface reflectance raised by 0.20 | Vanos, Kalkstein, Sailor et al., three-city report |
New York shows the largest absolute number of avoided deaths because of its population and density; Los Angeles showed the largest temperature drops of the three U.S. cities. With a smaller 0.10 reflectance increase, the same report modeled reductions of only 1 percent in Baltimore and Los Angeles and 9 percent in New York, and air temperature changes “commonly less than a 1°F decrease.” Percentages are not directly comparable across studies, which use different heat scenarios and methods.
What a reflective roof physically changes
A reflective roof cuts the heat entering both the building and the air above it. Cool roofs can remain about 50 to 60 degrees Fahrenheit (28 to 33 degrees Celsius) cooler than traditional materials in peak summer weather (EPA compendium, ch. 4), and in air-conditioned homes their solar reflectance can reduce peak cooling demand by 11 to 27 percent, per the EPA’s Using Cool Roofs to Reduce Heat Islands page. In non-air-conditioned homes, the same page reports maximum indoor temperatures 1.2 to 3.3 degrees Celsius (2.2 to 5.9 degrees Fahrenheit) lower.
At the city scale, the London model’s all-roof cool-roof scenario lowered mean near-surface air temperature by 0.8 degrees Celsius over summer 2018 (Nature Cities, 2024), and the West Midlands model cut city-center daytime air temperature during heat waves by 0.5 degrees Celsius on average and up to about 3 degrees Celsius (Macintyre and Heaviside, 2019). A cool-colored dark shingle is the middle option: LBNL reports that a cool-colored roof reflecting 35 percent of sunlight stays about 22 degrees Fahrenheit cooler than a traditional roof that looks the same but reflects 10 percent, so a homeowner who wants a charcoal or brown roof can still cut surface heat.
Methodology
This report synthesizes primary data from the U.S. EPA (Cool Roofs compendium chapter and Heat Islands program pages), the LBNL Heat Island Group, the CRRC chart of the 2025 California Energy Code, IECC 2021 section C402.3, CDC WONDER mortality data as analyzed in JAMA (2024), CDC MMWR emergency department data (2024), and modeling published in Nature Cities (2024), Environment International (2019 and 2025), Environmental Research Letters (2014) and the 2014 three-city heat-health report. The ranked table aggregates modeled mortality-reduction estimates normalized to percent reduction and, where reported, avoided deaths; figures were not re-computed. The Roofing Brief did not take field measurements.
Limitations
The mortality figures are modeled outcomes under specific heat scenarios and roof-conversion assumptions (albedo 0.7 to 0.85 on all roofs in the UK studies; a 0.10 or 0.20 reflectance increase, worth 1 to 21 percent, in the U.S. three-city study), not observed death counts, and they should be read as directional. Studies differ in method, baseline albedo and climate, so cross-city percentages are not strictly comparable. The 2023 death count of 2,325 is provisional in the JAMA analysis. Reflective roofs can raise winter heating use in cold climates. Field surface temperatures vary with slope, ventilation, aging and soiling. None of these figures is a guarantee for any single building or jurisdiction.
For the building-energy side of this question, see our companion report on how much reflective roofs save by climate.
For material and color context, see black shingles and heat, the most popular roof colors in America, sustainable roofing options including cool roofs, and green roof cost and load.
Related: Roofer Heat Illness and Heat Deaths (2026): The Deadliest Weather Risk on the Roof, by the Numbers
Frequently asked questions
What is the surface temperature of a black roof in summer sun?
Traditional dark roofs reach 150 to 185 degrees Fahrenheit (66 to 85 degrees Celsius) at summer peak, and standard black asphalt reaches 165 to 185 degrees Fahrenheit (74 to 85 degrees Celsius) at midday, per the EPA Cool Roofs compendium. That is 55 to 85 degrees Fahrenheit (31 to 47 degrees Celsius) above air temperature.
Do dark roofs really make cities hotter?
Yes, measurably. Traditional roofing reflects only 5 to 15 percent of sunlight, and roofs cover 20 to 25 percent of land in the EPA pilot cities, so their absorbed heat feeds the urban heat island that leaves U.S. cities about 1 to 7 degrees Fahrenheit warmer than outlying areas by day and 2 to 5 degrees Fahrenheit warmer at night (EPA).
How much cooler is a reflective roof than a dark roof?
Cool roofs can remain about 50 to 60 degrees Fahrenheit (28 to 33 degrees Celsius) cooler than traditional roofing in peak summer, per the EPA. LBNL reports a clean white roof reflecting 80 percent of sunlight stays about 55 degrees Fahrenheit cooler than a gray roof reflecting 20 percent.
Can cool roofs actually reduce heat deaths?
In modeling studies, yes. Estimated reductions run from 5 percent (Baltimore) to 32 percent (London, 249 avoided deaths in summer 2018), with up to 219 lives saved per decade in New York (Nature Cities, 2024; three-city heat-health report, 2014). These are modeled estimates, not guaranteed outcomes for any one city.
Are heat deaths in the US actually rising?
Yes. A JAMA analysis of CDC WONDER data counted 21,518 heat-related deaths from 1999 through 2023, rising from 1,159 in 2020 to a provisional 2,325 in 2023, the highest year in the series (Howard et al., 2024).
Do reflective roofs cause a winter heating penalty?
Small, in cold climates. The EPA says summer cooling savings typically offset the winter heating penalty because winter sun is lower and days shorter.