What precautions should I take when using the HOBO Pro Loggers outside?

The HOBO Pro series was manufactured for outdoor use. The loggers can be left outdoors with minimum precautions (important RH note below). Direct sunlight will heat the logger up giving you readings that are higher than ambient; therefore, when the logger is placed where direct sunlight may fall on it the logger should be placed under a solar radiation shield to record correct data.

The RH Sensor used on the HOBO Pro is designed for normal outdoor environments with cyclical high and low humidity levels. Saturation of the sensor is evident when the logger reads values of 100% RH or greater. Like all RH sensors, repeated saturation from exposure to condensing environments will lead to irreversible drift and eventually destroy the RH sensor. If this happens, the logger will need to be returned to Onset Computer Corp. for sensor replacement. The rate at which the degradation of the sensor occurs depends on the harshness of the environment to which the sensor is exposed. Condensing environments with the temperature above 30 °C (86 °F), exposure to salt spray, ammonia vapors, or some other chemicals will accelerate the sensor degradation.

When using the HOBO Pro Temp/RH, protect the logger so that direct moisture cannot hit the sensor, yet air can still flow through to give correct readings. The RH sensor should be facing downward, so condensation cannot build on the sensor, causing saturation.

The external temperature probe is not intended for prolonged use in water or moist soil.

Some protection options:

Solar Radiation Shield

Required for accurate temperature and RH measurements in locations exposed to solar radiation or reflective heat.

Rain Shield

Provides convenient mounting and rain protection for the RH sensor for the HOBO Pro Temp/RH.