Washington design temperatures
Outdoor heating and cooling design conditions for 16 Washington weather stations. Choose the station nearest to you in distance and elevation, and check whether your building department specifies its own values.
| Station | Elevation | 99.6 % heating | 99 % heating | 1 % cooling / MCWB | 0.4 % cooling / MCWB | Use it |
|---|---|---|---|---|---|---|
| BellinghamWMO 727976 · 1973–1996 | 157 ft | 18 °F | 22 °F | 76 / 64 °F | 80 / 66 °F | Load calculator |
| BremertonWMO 727928 · 1973–1996 | 482 ft | 22 °F | 27 °F | 84 / 65 °F | 88 / 66 °F | Load calculator |
| Fairchild AFBWMO 727855 · 1967–1996 | 2,461 ft | 3 °F | 9 °F | 88 / 62 °F | 92 / 63 °F | Load calculator |
| Fort Lewis/GrayWMO 742070 · 1967–1996 | 302 ft | 19 °F | 24 °F | 82 / 64 °F | 86 / 65 °F | Load calculator |
| HanfordWMO 727840 · 1973–1996 | 732 ft | 4 °F | 12 °F | 97 / 66 °F | 100 / 67 °F | Load calculator |
| Kelso-LongveiwWMO 727924 · 1990–1996 | 16 ft | 21 °F | 26 °F | 82 / 65 °F | 87 / 68 °F | Load calculator |
| McChord AFB/TacomaWMO 742060 · 1967–1996 | 322 ft | 20 °F | 25 °F | 81 / 64 °F | 85 / 65 °F | Load calculator |
| OlympiaWMO 727920 · 1973–1996 | 200 ft | 18 °F | 23 °F | 83 / 65 °F | 88 / 67 °F | Load calculator |
| Quillayute StateWMO 727970 · 1973–1996 | 203 ft | 23 °F | 26 °F | 75 / 61 °F | 81 / 63 °F | Load calculator |
| Seattle-TacomaWMO 727930 · 1967–1996 | 449 ft | 24 °F | 28 °F | 82 / 64 °F | 85 / 65 °F | Load calculator |
| Seattle/Boeing FieldWMO 727935 · 1973–1996 | 16 ft | 23 °F | 28 °F | 82 / 64 °F | 86 / 66 °F | Load calculator |
| SpokaneWMO 727850 · 1973–1996 | 2,366 ft | 0 °F | 7 °F | 89 / 62 °F | 92 / 63 °F | Load calculator |
| Spokane/FeltsWMO 727856 · 1973–1996 | 1,952 ft | 4 °F | 10 °F | 91 / 64 °F | 95 / 66 °F | Load calculator |
| Walla WallaWMO 727846 · 1973–1996 | 1,204 ft | 4 °F | 12 °F | 95 / 66 °F | 99 / 67 °F | Load calculator |
| Wenatchee/PangbornWMO 727825 · 1973–1996 | 1,243 ft | 4 °F | 10 °F | 92 / 64 °F | 95 / 65 °F | Load calculator |
| YakimaWMO 727810 · 1973–1996 | 1,066 ft | 3 °F | 10 °F | 92 / 65 °F | 96 / 66 °F | Load calculator |
Using these values
- Heat-loss calculations for homes commonly use the 99 % heating value, and cooling loads the 1 % dry bulb with its mean coincident wet bulb (MCWB). The 99.6 % and 0.4 % values are more conservative.
- “Load calculator” opens the heating and cooling load calculator with that station’s 99 % and 1 % temperatures and its design moisture difference (outdoor air at the 1 % condition versus 75 °F, 50 % RH indoors, at the station’s elevation).
- Source: U.S. Air Force Combat Climatology Center and NOAA National Climatic Data Center, Engineering Weather Data (1999; public domain). Each station’s period of record is shown under its name; they end by 1996, and the climate has warmed since, so check local requirements before relying on a value for a permit.