Methodology
How the simulation works
Every image on this site is a model simulation, not a photograph. We turn 30 years of local climate data into a handful of wear drivers, grow each kind of damage at a rate set by those drivers, and draw the result procedurally. Climate data last refreshed: 2026-11-12.
1. Climate data
- NOAA NCEI U.S. Climate Normals, 1991–2020 (monthly). For each city we use the nearest weather station that publishes complete normals, preferring airport stations. From it: mean monthly temperature, days with at least 0.01 in of precipitation, days with a minimum at or below 32 °F, days with a maximum at or below 32 °F and days at or above 90 °F.
- NASA POWER (daily point data). Mean relative humidity, solar irradiance and an all-sky UV index (UV available from 2001). Grid cells are about 50 km wide, so we take temperature extremes from stations instead.
- Coastal exposure is a simple 0–2 flag per city for salt air.
2. Wear drivers
- Decay hazard: the Scheffer (1971) climate index — the sum over months of (mean °C − 2) × (rainy days − 3), divided by 16.7. Below 35 is low, 35–65 moderate, above 65 high.
- Freeze–thaw days: days whose minimum is at or below freezing but whose maximum is above it.
- Sun: a blend of UV index and solar irradiance; heat: days at or above 90 °F; humidity: mean relative humidity.
3. Material behavior
Each material has its own damage layers and rates: untreated cedar grays within months and then bleaches (sun), checks (sun, frost, heat), grows mildew (decay hazard, humidity) and finally rots at board ends or post bases. Capped composite fades early, then stabilizes, and can grow surface mildew in damp climates. The rates are calibrated so national results land inside published typical-life ranges (cedar deck 15–20 yrs; composite deck 25–30 yrs; wood fence 15–20 yrs), drawing on USDA Forest Products Laboratory guidance on above-ground decay and weathering of wood.
4. Limits
- The scenario is a south-facing surface in full sun with no special detailing. Shade, drainage, ground contact, wood quality and installation change real results a lot.
- Expected-life ranges are model estimates, not warranties or inspections.
- Grid data can blur coastal and mountain cities; station distance is listed below.
Stations used
| City | NOAA station | Distance | Rainy days | Decay index | Freeze–thaw days | Days ≥ 90 °F | Humidity |
|---|---|---|---|---|---|---|---|
| Albuquerque, NM | ALBUQUERQUE INTL AP · USW00023050 | 5.3 km | 56.1 | 22.2 | 90.7 | 64.4 | 43.41% |
| Atlanta, GA | ATLANTA FULTON CO AP · USW00003888 | 12.8 km | 123.4 | 79.5 | 51.5 | 54 | 76.32% |
| Austin, TX | AUSTIN-CAMP MABRY · USW00013958 | 6 km | 85.8 | 53.9 | 11.4 | 122.9 | 69.02% |
| Boston, MA | BOSTON · USW00014739 | 4.1 km | 128.4 | 48.3 | 68.4 | 14.1 | 80.11% |
| Buffalo, NY | BUFFALO · USW00014733 | 13.4 km | 165.8 | 52.8 | 75.1 | 3.4 | 78.61% |
| Charleston, SC | DWTN CHARLESTON · USW00013782 | 0.8 km | 101.9 | 73.7 | 6.2 | 24.5 | 78.16% |
| Chicago, IL | CHICAGO MIDWAY AP · USW00014819 | 14.9 km | 121.3 | 55.3 | 67.1 | 19.8 | 80.96% |
| Dallas, TX | DALLAS FAA AP · USW00013960 | 7.3 km | 82.2 | 47.4 | 21.8 | 107.6 | 69.16% |
| Denver, CO | DENVER-STAPLETON · USW00023062 | 10.6 km | 84.4 | 34.2 | 135.1 | 42.1 | 49.89% |
| Houston, TX | HOUSTON WILLIAM P HOBBY AP · USW00012918 | 15.3 km | 107.2 | 84.5 | 4.2 | 100.5 | 77.22% |
| Las Vegas, NV | LAS VEGAS AIR TERMINAL · USW00053123 | 6.7 km | 22.5 | 0.4 | 10.8 | 136.2 | 31.55% |
| Los Angeles, CA | LOS ANGELES DOWNTOWN/USC · USW00093134 | 5.5 km | 34.1 | 8.5 | 0 | 25.5 | 57.35% |
| Miami, FL | MIAMI INTL AP · USW00012839 | 13.1 km | 141 | 155.8 | 0 | 91.5 | 75.86% |
| Minneapolis, MN | MINNEAPOLIS-ST PAUL INTL AP · USW00014922 | 11 km | 118.8 | 47.2 | 74.8 | 12.6 | 77.13% |
| Mobile, AL | MOBILE DWTN AP · USW00013838 | 8.7 km | 133.4 | 110.2 | 15.1 | 73 | 79.15% |
| Nashville, TN | NASHVILLE INTL AP · USW00013897 | 9.9 km | 123.1 | 70.7 | 60 | 54.2 | 77.48% |
| New Orleans, LA | NEW ORLEANS AUDUBON · USW00012930 | 6.9 km | 114.5 | 100.9 | 3.8 | 105.6 | 78.96% |
| New York, NY | NY CITY CNTRL PARK · USW00094728 | 8.4 km | 125.4 | 59.5 | 51.2 | 17.4 | 80.16% |
| Phoenix, AZ | PHOENIX AP · USW00023183 | 6.6 km | 33.4 | 7.2 | 0.6 | 173.4 | 34.21% |
| Portland, OR | PORTLAND INTL AP · USW00024229 | 10.1 km | 157 | 56.6 | 30.1 | 14.6 | 81.7% |
| Salt Lake City, UT | SALT LAKE CITY INTL AP · USW00024127 | 6.4 km | 91.5 | 23.3 | 91.1 | 62.3 | 59.46% |
| San Diego, CA | SAN DIEGO INTL AP · USW00023188 | 2.6 km | 40.3 | 12 | 0 | 3.1 | 62.96% |
| San Francisco, CA | SAN FRANCISCO DWTN · USW00023272 | 0.6 km | 71.2 | 26.7 | 0 | 3.3 | 77% |
| Seattle, WA | SEATTLE BOEING FLD · USW00024234 | 7.3 km | 154.2 | 52.6 | 29 | 3.1 | 83.15% |
| Tampa, FL | TAMPA INTL AP · USW00012842 | 8 km | 108.2 | 103.6 | 0.7 | 94.2 | 77.72% |
Sources: NOAA NCEI U.S. Climate Normals 1991–2020; NASA Langley POWER project.
Download the data
The per-city values above, plus monthly temperatures and rainy days, are available as JSON and CSV.
License & reuse
Our derived dataset, the simulation images and the rankings are published under Creative Commons Attribution 4.0 (CC BY 4.0). You may republish them, including commercially, as long as you credit howitweathers.com with a link to the page you used. The underlying NOAA and NASA data are public. For press or other licensing questions: hello@howitweathers.com.