Add wind and humidity to the forecast.
Wind chill describes heat loss from exposed skin in wind; it does not cool objects below the air temperature. Heat index values assume shade and light wind; direct sun raises the felt heat. Neither index accounts for clothing, exertion, wet skin or acclimatisation. Follow official warnings.
Model details & unit conventions ↗Wind chill formula for hikers in °F and °C, with a chart in °C and km/h, worked examples, the NWS limits and what the index does not include.
Heat index for hiking explained: the NWS formula, a °C version of the NWS categories, a worked example at 32 °C and 60%, and the limits of shade-based readings.
Pitch a tarp for wind by lowering the ridge, turning an open end away from the wind and keeping guylines tight, with the cost in headroom.
Temperature drop with altitude per 1,000 m and per 1,000 ft, from NASA’s standard-atmosphere equation and NWS lapse rates, with a trailhead example.
Why a phone or power bank delivers less energy in cold weather, how to model the loss as a lower efficiency scenario, and what to do on the trip.
The ten essentials for hiking as ten systems, with the problem each one solves, links to Trailwright guides and tools, and how to scale the list.
Related toolsWater decisionsPower budgetAltitude