Weather Signs Field Card
Weather moves faster than forecasts. Learn the local signs and you'll know what's coming 2–6 hours before it arrives — long enough to set a rain fly, shorten a hike, or get back to camp.
Cloud Types — What They Signal
Cumulus
Puffy white cauliflower clouds, flat base, sharp edges.
Fair weather
Cumulonimbus
Towering anvil-top cloud, dark base, can span horizon.
Storms coming
Cirrus
Thin, wispy streaks high in the sky.
Change in 24–48h
Stratus
Low, flat grey blanket covering the sky.
Drizzle likely
Altocumulus
Rippled rows of grey-white puffs at mid height.
Storms possibleWind Signs
- Sudden calm after breezeA squall line may be approaching. Look for a dark shelf cloud on the horizon.
- Wind shifting to the southWarm front approaching — rain likely within 12 hours.
- Backing wind (clockwise to counter-clockwise)Deteriorating conditions. Watch the sky.
- Steady strong wind from the westUsually clearing weather following a front. Good sign.
Sky Color Rules
- Red sky at nightSailors' delight. High pressure moving in from the west — fair weather ahead.
- Red sky in morningSailors take warning. Moisture moving in from the west — rain likely.
- Yellow/green sky before sunsetHail or tornado risk in severe weather regions. Seek shelter.
- Dark purple horizon to the westHeavy rain cell approaching. Set up rain protection now.
6-Hour Decision Tree
Carry onCumulus only, wind steady from west or northwest, no anvil clouds visible, barometer steady or rising.
Set rain fly nowCirrus building, wind backing, altocumulus ripples appearing, humidity rising noticeably.
Shorten hike / head inCumulonimbus on horizon, sudden wind shift, darkening base cloud, thunder audible (any distance).