Bat Houses and Temperature

Temperature is one of the most important ingredients in bat house success, and probably the least understood. Unpainted bat houses and those mounted in the shade are seldom warm enough, and thus are rarely used. Many bat house owners needlessly worry that their bat houses will get too warm. Available evidence suggests the opposite. Unless you live in an exceptionally hot climate, you can help an underheated bat house by moving it to a sunnier spot and painting it a darker color after carefully caulking all exterior joints.

Actual bat house color is less important than darkness. Dark houses absorb more solar radiation, thus warming them better. The ambient, or outside, temperature is affected by factors such as cloud cover, prevailing winds, elevation, latitude, and topography, making earlier painting suggestions based solely on latitude too simplistic. Our latest recommendations are based on the average high temperature in July for your area. Because temperatures are averaged, the value may be lower than you expected. You can obtain specific information from your local weather bureau or university, or use a published reference such as the Climatic Atlas of the United States. The map to the left, while not very detailed, provides a good starting point.

Bat houses may overheat, especially in the south, but the latest BCI designs, with roofs and vents, are designed to greatly reduce that possibility. It is probably better to err on the side of warmth when painting and locating a bat house. Later you can extend the roof, add more vents, or paint the bat house lighter if needed.

Bat House Color Recommendations and Average Daily
High Temperatures in July in the U.S.


Black areas = less than 85° F. -- Recommend black paint.
Dark areas = 85°-95° F. -- Recommend dark shade of paint.
Medium areas = 95°-100° F. -- Recommend medium shade of paint.
Light areas = 100° F or greater. -- Recommend light shade of paint.

GRAPHIC BY JIM KENNEDY