Humidity

The iButton of Type 23 can log both temperature and humidity

ibutton Hydrochron Humidity temperature data logger 
iButton Type 23
Temperature Range: -20 to 85 °C
Precision: +/- 1 °C
Humidity Range:   0 to 100 % RH
Memory: 
4,096 values at high resolution
8,192 values at low resolution

Refer to the iButton page for specs and pricing.