Weather stations are sophisticated weather monitoring systems which read indoor and outdoor temperatures, barometric pressure, humidity, wind speed and direction, rainfall, dew point, wind chill and even outdoor brightness. Weather stations are available in wall-mountable designs or desktop versions - which resemble palm pilots. Some weather stations have alarms which indicate changes in weather, and some even emit storm warning alerts. Another interesting feature of this product is data tracking, which allows you to review the weather history over different periods and view it in charts. Cable-free and wireless versions of weather stations are available and run on solar power, battery backup and an AC adapter. The simplest weather stations cost about $60 online, although they can cost up to $700 depending on their features.