We've been lucky to have several days of hoarfrost here in Southcentral Alaska. According to Accuweather, "...frost or hoarfrost forms when moisture in the air skips the water droplet stage and appear directly as ice crystals on an object.....Frost and hoarfrost can only form when the air and objects are at or below freezing." (See their whole post at https://www.accuweather.com/en/weather-news/what-is-hoarfrost/7092.)
Hoarfrost is one of the things I enjoy about winter. It makes everything look beautiful. Here are a few photos for you--enjoy!