Testo 176 H2 Temperature and Humidity Data Logger

Amazon

Data storage for up to 2 million readings, up to 8 years battery life Measure humidity and temperature on two channels thanks to two ports for external sensors Robust metal housing and protection against dust and water jets according to protection class IP 65 Three software versions are available for measurement data analysis on the PC, basic software can be downloaded for free

Test-meter.co.uk

Professional dual-channel data logger. Tracks temperature (-20˚C to 70˚C) and humidity (0-100% RH). 2M reading memory. 8-year battery. USB/SD data transfer. IP68 metal casing. Ideal for storage/transport monitoring.