The weather station is a Davis Instruments wireless Vantage Pro2.
The picture above is of the Integrated Sensor Suite (ISS). The black cylinder in the picture is the rain gauge collector. The temperature and humidity sensor are in the white radiation shield beneath the rain collector. Davis states that the accuracy is ±1 F for temperature, ±3% for outside relative humidity, ±1 mb in pressure, 0.01 inch for rainfall (one tip of bucket), and ±2 mph for wind speed.
An indoor console receives the data from the ISS via a spread spectrum 916 MHz radio link. The console measures the barometric pressure, and the indoor temperature and humidity. A data logger attached to the console saves the data. A Windows computer downloads the data from the logger with Davis WeatherLink software, and sends ascii data to the Linux server computer. A shell script on the server computer makes the graphs, collects the statistics, and formats the web page.