Heat days ≥100°F1,095
Freeze days ≤32°F19
Reported hail days ≥1″24
Reported hail days ≥2″1
Reported severe-wind days ≥50 kt116
Cumulative solar exposure21.372016–2025 total · MWh/m²
Same roof. Same birthday. Different decade.
Roof Year Same roof. A brighter picture.
Same roof. Same birthday.
Different decade.
Roofs installed in the same year can live through very different histories
of heat, freeze, hail, wind, and solar exposure.
Same roof. Different skies.
Maricopa County, AZ
Hotter. Brighter. Longer sun.
Pennington County, SD
Cold. Windy. Tough seasons.
Imperial County, CA
Desert heat. Clear skies.
Fall River County, SD
Cold. Hail. High winds.
Heat days ≥100°F0
Freeze days ≤32°F1,756
Reported hail days ≥1″130
Reported hail days ≥2″34
Reported severe-wind days ≥50 kt112
Cumulative solar exposure15.792016–2025 total · MWh/m²
Heat days ≥100°F1,204
Freeze days ≤32°F1
Reported hail days ≥1″0
Reported hail days ≥2″0
Reported severe-wind days ≥50 kt14
Cumulative solar exposure21.532016–2025 total · MWh/m²
Heat days ≥100°F73
Freeze days ≤32°F1,890
Reported hail days ≥1″48
Reported hail days ≥2″8
Reported severe-wind days ≥50 kt76
Cumulative solar exposure16.012016–2025 total · MWh/m²
County totals for 2016–2025. Hail and wind are reported county-days. Solar exposure is cumulative irradiation for the full period.
A closer look
Maricopa vs.
Pennington
Same roof. Same year.
A very different history.
Maricopa County, AZPennington County, SD
Heat days ≥100°F
Freeze days ≤32°F
Reported hail days ≥1″
Reported hail days ≥2″
Reported severe-wind days ≥50 kt
Cumulative solar exposure
Bar lengths use each measure’s fixed national maximum for 2016–2025. Values remain directly labeled.
THE IMPACT
How weather history can affect roof performance
Published research links heat, UV exposure, thermal cycling, hail, and wind loading to how asphalt-shingle systems weather over time. Roof Year shows exposure context — not a direct roof-life prediction.
LEARN MORE ABOUT THE RESEARCH →High heat & solar weathering
Laboratory weathering exposes shingles to UV alongside controlled temperature and humidity, with measurable physical and chemical changes. Roof Year’s county heat and solar totals do not measure those material changes.
Research fact: UV, temperature, and humidity are studied together under controlled conditions. NIST 2026 →
Laboratory weathering evidence
Freezing conditions
Research discusses freeze–thaw cycling as a general material-weathering mechanism. Roof Year counts county-days with a daily minimum at or below 32°F; it does not measure cycles or establish roof damage.
Research context: Thermal cycling is discussed as a general durability stressor.
Context, not a roof finding
Prior hail exposure
Controlled tests found greater granule-loss responses in weathered or conditioned specimens than in new specimens. Results are specific to the products and test setups studied.
Research fact: Prior weathering changed later material response under specific hail tests. Frontiers in Materials 2025 →
Test-specific material response
Severe winds
IBHS found that many tested products began declining in wind performance between years five and ten. The rate and severity varied widely by product.
Research fact: Product, climate, roof orientation, and shingle unsealing can affect measured performance. IBHS 2026 →
Performance varies by product and exposure
Research boundary: County exposure does not determine exact roof condition, remaining life, years lost, replacement timing, damage probability, or a combined score.
THE BIG PICTURE
A national range
of roof exposures
The lowest and highest county totals in the United States, with the four roof histories above held against the same frame.
SAME COUNTY.
A WIDER RANGE
OF REALITY.
A WIDER RANGE
OF REALITY.
Heat days ≥100°F
≥100°F
03016029031,204MARPEN · 0IMPFR
Freeze days ≤32°F
≤32°F
06911,3812,0722,762MARPENIMPFR
Reported hail days ≥1″
reported county-days
0336598130MARPENIMP · 0FR
Reported hail days ≥2″
reported county-days
09172634MARPENIMP · 0FR
Reported severe-wind days ≥50 kt
≥50 kt
03570104139MARPENIMPFR
Cumulative solar exposure
MWh/m² · 2016–2025 total
8.6612151821.65MARPENIMPFR
MAR — Maricopa County, AZPEN — Pennington County, SDIMP — Imperial County, CAFR — Fall River County, SD
What has your roof lived through?
Choose your county and installation year to see the recorded weather history since then.
Check your roof’s weather history →Trusted science
Methods & data
Built from authoritative public datasets for the fixed 2016–2025 research benchmark. Every figure is a county total, not a property measurement.
Learn more about our methods →Data & Press →
NOAA Storm Events
Reported hail and thunderstorm-wind events, collapsed to distinct county-days.
Storm Events Database →
U.S. Census TIGER/Line
U.S. Census TIGER/Line provides the 2025 county geometry used by the Explorer.
census.gov →Storm Events reporting changed around 2010. Recorded weather does not establish that any individual roof was struck or damaged. NASA POWER measures irradiation, not roof temperature.
Roof Year
Same roof. Same birthday. Different decade.
Roofs installed in the same year can live through very different histories of heat, freeze, hail, wind, and solar exposure.
Same roof. Different skies.
Maricopa County, AZ
Hotter. Brighter. Longer sun.
Imperial County, CA
Desert heat. Clear skies.
Fall River County, SD
Cold. Hail. High winds.
County totals for 2016–2025. Hail and wind are reported county-days. Solar exposure is cumulative irradiation for the full period.
How weather history can affect roof performance
Published research links heat, UV exposure, thermal cycling, hail, and wind loading to how asphalt-shingle systems weather over time. Roof Year shows exposure context — not a direct roof-life prediction.
High heat & solar weathering
Laboratory weathering exposes shingles to UV alongside controlled temperature and humidity, with measurable physical and chemical changes. Roof Year’s county heat and solar totals do not measure those material changes.
NIST 2026 →Freezing conditions
Research discusses freeze–thaw cycling as a general material-weathering mechanism. Roof Year counts county-days with a daily minimum at or below 32°F; it does not measure cycles or establish roof damage.
Prior hail exposure
Controlled tests found greater granule-loss responses in weathered or conditioned specimens than in new specimens. Results are specific to the products and test setups studied.
Frontiers in Materials 2025 →Severe winds
IBHS found that many tested products began declining in wind performance between years five and ten. The rate and severity varied widely by product.
IBHS 2026 →Research boundary: County exposure does not determine exact roof condition, remaining life, years lost, replacement timing, damage probability, or a combined score.
What has your roof lived through?
Choose your county and installation year to see the recorded weather history since then.
Check your roof’s weather history →Methods & data
Built from authoritative public datasets for the fixed 2016–2025 research benchmark. Every figure is a county total, not a property measurement.
Learn more about our methods →Data & Press →