Weather
Predict overnight frost
Frost catches campers by surprise. A few end-of-day cues warn you to insulate harder before dark.
Step-by-step
Check the sky at sunset — a clear sky lets ground heat radiate to space; frost is likely if temperatures are near freezing and skies stay clear all night.
Note the wind — dead calm plus clear skies plus low humidity is the classic frost recipe.
Camp higher on a slope rather than in a valley or hollow — cold air pools in low spots and frost hits them first.
If temperature drops below about 40°F (4°C) at sunset with clear skies and calm wind, prepare for frost by dawn.
Cover any exposed water containers and stow water bottles inside your sleeping bag so they don't freeze.
Tip: Look for spider webs beaded with dew at sunset — visible dew often means the air is cooling toward the dew point and frost is possible if temperatures keep falling.
Related outdoor skills
Educational reference only. Wilderness conditions change fast — practice in low-stakes settings, take a certified wilderness first-aid course, and confirm regional regulations before you rely on any of these skills in the field.