Mold inspection and indoor air help in Salem, OR
We do not keep an office in Salem. Every job starts with a free call. For large and complex properties in the Salem area we travel to you; for smaller jobs we tell you exactly what to ask for and point you to a local inspector we are comfortable recommending.
What the Salem climate does to a house
Measured at NOAA's Salem weather station.
- At the NOAA Salem station, mornings average 84 percent relative humidity across the year, and afternoons 59 percent.
- The dampest mornings come in November, averaging 88 percent. Afternoons are driest in July, at 39 percent.
- A normal year brings 39.67 inches of precipitation over about 144 days, with the most in December (6.86 inches).
- In 12 of 12 months the average morning humidity is 80 percent or higher.
- Even in the afternoon, average humidity stays above 60 percent in 6 of 12 months. Indoors, 60 percent is the line where mold starts to find it easy.
| Month | Morning RH | Afternoon RH | Precip. (in) | Days with precip. | Mean temp (°F) |
|---|---|---|---|---|---|
| January | 87% | 77% | 5.96 | 18 | 41.2 |
| February | 87% | 69% | 4.56 | 16 | 43.1 |
| March | 85% | 62% | 3.99 | 17 | 46.9 |
| April | 84% | 56% | 2.81 | 14 | 50.4 |
| May | 83% | 53% | 2.22 | 11 | 56.2 |
| June | 82% | 49% | 1.55 | 8 | 61.6 |
| July | 80% | 39% | 0.46 | 3 | 67.6 |
| August | 80% | 39% | 0.45 | 3 | 67.6 |
| September | 82% | 44% | 1.28 | 7 | 62.6 |
| October | 87% | 61% | 3.03 | 12 | 53.2 |
| November | 88% | 77% | 6.50 | 17 | 45.5 |
| December | 88% | 81% | 6.86 | 19 | 40.1 |
Source: NOAA National Centers for Environmental Information, Comparative Climatic Data: average relative humidity (period of record through 2018), normal precipitation, mean temperature and cooling degree days (1981 to 2010 normals), and mean days with 0.01 inch or more of precipitation, 90 degrees or more, and 32 degrees or less. Last updated September 27, 2026.
Where moisture hides in Salem homes
Winter condensation in the attic
Warm, moist indoor air leaking into a cold attic condenses on the roof sheathing. The result is frost in January and dark staining on the underside of the roof by spring. Here about 54 days a year drop to 32°F or below.
Humid summers in basements
Basements stay cool, so humid summer air that reaches them hits the dew point. Musty basements and mold on stored items are the classic sign. Summer mornings here average 81 percent humidity.
Snowmelt and spring rain
Water that pools against the foundation during the thaw finds cracks and gaps and wicks into finished basements. A normal year brings 39.67 inches of precipitation.
Tight houses with little fresh air
Homes sealed up for winter trap cooking and shower moisture. Windows run with condensation and the corners of exterior walls grow mold. Winter afternoons here average 76 percent humidity outdoors.
Common questions from Salem
Large, custom or multi-property situations: see Keystone.
Mold or air problem in Salem?
Start with a free 15 minute call. We will tell you what you need, whether that is a local inspector, a virtual consultation or an on-site investigation.