Tempest is a sensor that automatically measures and logs exposure to temperature, humidity, UV, and fresh and saltwater. By leveraging ultra-low power electronics and careful design, Tempest can achieve a battery life of more than 15 years. By default, it records the total on time, along with the total operating time spent within bands of exposure, such as between 50 and 60°C or within 70-80% relative humidity. Tempest can be configured to record time histories of any or all of the sensing channels, with configurable recording rates. All data can be easily accessed via NFC using our Android app.