Swan Valley Idaho Frost Dates   5396′ altitude   Last average frost June 17, first average frost September 3.   78 frost free days.

• Light freeze 29°F to 32°F tender plants killed
• Moderate freeze 25°F to 28°F widely destructive to most vegetation
• Severe freeze 24°F and colder heavy damage to most garden plants

USDA Hardiness zone  5a    The coldest temperatures are -20° to -15F