Rocky Talkies were designed to operate in harsh conditions. They have been thoroughly tested and can be reliably used down to -20˚F without significant loss in battery life. All Lithium-ion batteries experience reduced life in cold weather, and temperatures below -20˚F can have significant effects on battery life. While the radios can be operated down to -20˚F, make sure to only charge the radios at temperatures between 0˚to 100˚F to not damage the battery.