SparkFun Weather Shield
https://www.sparkfun.com/products/12081
The Weather Shield is an easy to use Arduino shield that grants you access to barometric pressure, relative humidity, luminosity and temperature. There are also connections on this shield to optional sensors such as wind speed, direction, rain gauge and GPS for location and super accurate timing.
These Weather Shields utilize the HTU21D humidity, MPL3115A2 barometric pressure, and ALS-PT19 light sensors and relies on the HTU21D and MPL3115A2 Arduino libraries. Each shield comes with two unpopulated RJ11 connector spaces (for optional hook up of rain and wind sensors) and a 6-pin GPS connector (for optional hook up of a GP635T GPS module). Finally, each Weather Shield can operate from 3.3V up to 16V and has built in voltage regulators and signal translators.
See also Weather Meters