What to wear on Mauna Kea
You are driving from a beach to somewhere that sits below freezing after dark most of the year. Here is tonight's actual number, not a seasonal average.
Forecast for tonight
50°F
Visitor Station, once it is dark
This is the NWS forecast averaged over tonight's dark hours, which is what you should dress for. The measured readings below are useful, but during the day they describe an afternoon you will not be standing in.
Measured right now
Visitor Station · 9,200 ft
56°F
HP · 5:44 PM HST
Summit area · 13,800 ft
47°F, feels like 40°F in the wind
CFHT/GEM · 5:44 PM HST
So, tonight
Cold
- A proper insulated jacket, not a hoodie. It will be colder by midnight than it is now.
- Long trousers, closed shoes, and something for your hands. Standing still in the dark is much colder than walking around.
- A hat. Most of what you lose, you lose from your head, and there is nothing to block the wind up there.
Why it catches people out
The Visitor Station is at 9,200 ft. It runs roughly 30°F colder than Kona on the same afternoon, and it keeps dropping after dark while you stand still watching the sky.
The summit is colder again, and windier. The two altitudes are genuinely two different nights, which is why both are listed above rather than averaged into one number.
Wind is most of it. Our feels-like figure is the NWS wind chill, computed from the gust rather than the mean, because the gust is what you are actually standing in.
The list, if you want one
- Insulated jacket, ideally windproof.
- Warm hat and gloves.
- Long trousers, thick socks, closed shoes.
- A blanket for sitting on or wrapping up in.
- Water. Altitude dehydrates you faster than you notice.
- A red torch if you have one, or red cellophane over a normal one. White light wrecks everyone's night vision including your own.
Tours hand out parkas at the trailhead, which is a real part of what you are paying for. If you are driving yourself, that part is on you.
How cold it will be on each of the next seven nights →
Temperature and wind: Maunakea Weather Center station readouts at Hale Pōhaku and the summit. Wind chill computed with the NWS 2001 formula, which does not apply above 50°F or under 3 mph, and is left blank rather than extrapolated.