Not inexpensive, but I purchased the most affordable BroodMinder sensor which measures the internal hive temperature. The sensor is a thin profile temperature data logger that rests on the top bar and syncs with my iPhone (then uploads to the cloud) where data is graphed and accessible on my iPhone or web browser.
The dashed red line is local weather data. I'm naturally skeptical about weather data. When I placed the broodminder in hives without bees, I found that temperature data tracked the weather data accurately.
Hourly internal temperature data values from the sensor created the solid cranberry-colored line. Ideally the solid line tracks within the gray band (92°F - 98°F) and represents a queen-right hive. There are many reasons why the solid line is drawn below the gray band, but I had no information as to why the temperature had climbed above the gray band to 105°F. I'm puzzled and reached out to BroodMinder Support and Theresa Martin (author of Dead Bees Don't Make Honey) for assistance in shaping a theory.
I checked the sync with the iPhone which recorded the coin battery strength. Nothing suspicious there, the battery was 97% of full strength.
During the inspection of the counting board and an internal hive inspection, I discovered that the small hive beetles had compromised the honey. The 105°F was likely created by the fermentation of honey. I found the BroodMinder sensor and temperature graphs very helpful, internal temperature is one of many ways to monitor hive health.
