Environmental monitoring systems that include base stations and environmental sensor units (ESUs) that communicate in a wireless sensor network. A base station may include environmental sensors and may communicate with a remote server using a wide-area wireless network. The base station may also communicate with an environmental sensor unit using a wireless personal area network. The ESU may include environmental sensors and may communicate with the remote server via the base station. The base station and ESU may be adapted to automatically pair with one another to enable the ESU to communicate via the base station. An ESU may also be adapted to process data regarding environmental conditions by automatically determining a type of environmental sensor from which the data was received and processing the data based on the type. An ESU may also include physical ports by which new sensors can be connected to the ESU.