There is no weather station on the summit of Mt Whitney (14,505 ft / 4,421 m). Every summit number is an estimate. It blends three independent methods, and each one is shown above so you can see when they disagree.
1. Free air at summit height
Two weather models (GFS/HRRR and ECMWF, via Open-Meteo) give temperature and wind at the pressure levels around the summit (about 600 hPa). These are interpolated to 4,421 m using each day's actual level heights. This method also supplies the summit wind and the freezing level. No surface correction is applied. On average the free air matches the ground, but it runs about 2 °C (4 °F) too cold on sunny afternoons and too warm on clear nights.
2. Live station lapse fit
Every quality-checked station within 80 km, mostly between 3,600 and 11,500 ft, goes into a robust straight-line fit of temperature against elevation. That line is extended up to the summit. Closer stations count more, and the east and west slopes are fitted separately when possible. On calm, clear nights cold air pools in the valleys. When that inversion shows up, the valley stations are left out. This method only describes the present, and it reaches about 3,000 ft above the highest station.
3. Point forecast, corrected to summit height
The National Weather Service forecast for the summit's grid cell is valid at about 12,100 ft. It is corrected upward using the lapse rate from method 2, then averaged with Open-Meteo's forecast at summit height. Precipitation, snowfall, cloud and the sky wording come from these forecasts.
Blending
- Now uses all three methods, starting at 40 / 35 / 25 %. A method loses weight the further it is from the others.
- The 72-hour forecast uses methods 1 and 3 (60 / 40 %). The first few hours are nudged toward the live station fit.
- Low–high band: the spread of the methods, plus at least ±1.5 °C (±3 °F). It grows to ±2.5 °C by 72 hours and widens when the models disagree. Treat the band, not the single number, as the answer.
- Gusts are the free-air wind times the gust ratio from the surface forecasts. Wind chill uses the NWS formula. The freezing level is the highest point where the model profile crosses 0 °C (32 °F).
How well does it work?
Tested at the nearest working high stations: at Barcroft (12,410 ft) the forecast blend was off by 1.8 °C (3.2 °F) on average, and the live blend by 1.1 °C (2 °F). Expect larger errors at Whitney, which sits farther above the stations the fit relies on. Wind on the exposed summit ridge can be much stronger than any of these sources show.