This extension display the felt temperature (in °C or °F) as an icon in your chrome browser.
In humid conditions, the air feels hotter than it actually is, because of the reduction of perspiration. In windy conditions, the air feels cooler than it actually is, because of increased perspiration.
This extension requests your permission to access...
1. your physical location, only as a parameter to obtain weather data, and
2. api.wunderground.com, which is the source of weather data.
(Related concepts: apparent temperature, wind chill, heat index/humidex/humiture)