Summit forecast for 4,902 ft · Twin · Updated 3x daily
As of July 21, 2026
South Twin Mountain (4,902 ft) is currently 51°F (feels like 42°F) with overcast and SSE winds at 14 mph, gusting to 28 mph. Today's freezing level is 13,222–14,108 ft. Expect the summit to run about 8°F colder than the trailhead. Trail conditions are rated Difficult.
Valley forecasts don't apply up high — temperatures drop about 2.6°F per 1,000 ft on South Twin Mountain.
| Elevation | Temp Range | Max Wind | Wind Chill (Low) |
|---|---|---|---|
| Summit 4,902 ft | 54° – 59°F | 45 mph | 54°F |
| Treeline 4,000 ft | 56° – 61°F | 40 mph | 56°F |
| Trailhead 2,000 ft | 61° – 67°F | 21 mph | 61°F |
Freezing level today: 13,222–14,108 ft
~2.6°F drop per 1,000ft
Tap a day header to expand to 3hr or hourly detail
Today Jul 21 | Tomorrow Jul 22 | Thursday Jul 23 | |||||||
|---|---|---|---|---|---|---|---|---|---|
| AM | PM | night | AM | PM | night | AM | PM | night | |
| Temperature & Wind | |||||||||
| Weather | cloudy | rain | rain | fog | cloudy | cloudy | cloudy | ptly cloudy | sunny |
| Temp °F hi / lo | 56° 55° | 58° 55° | 59° 56° | 56° 54° | 57° 53° | 53° 38° | 42° 36° | 53° 44° | 51° 50° |
| Chill °F | — | — | — | — | — | 26° | 23° | 35° | 44° |
| Wind mph | 30 | 45 | 37 | 33 | 30 | 28 | 31 | 23 | 20 |
| Gust mph est. | 48 | 63 | 59 | 53 | 48 | 45 | 50 | 37 | — |
| Storm risk | — | — | — | mod | mod | — | — | — | — |
| Precipitation | |||||||||
| Precip in (rain/snow) | - | 0.6 | 0.6 | - | - | - | - | - | - |
| Freezing ft | 13,698 ft | 13,061 ft | 9,024 ft | ||||||
| Conditions | |||||||||
| Cloud cover | 100% | 100% | 100% | 100% | 100% | 100% | 100% | 55% | 5% |
| Vis mi | clear | 0.1 | <0.1 | <0.1 | 9 | 8 | clear | clear | clear |
| UV | 6 | 7 | — | 2 | 7 | — | 4 | 8 | — |
Tap a day header to expand AM/PM/Night detail
| Elevation | Today Jul 21 | Tomorrow Jul 22 | Thursday Jul 23 |
|---|---|---|---|
| lo/hi °F · wind mph & dir · chill °F | |||
| Summit 4,902 ft | 55/56° 30 | 54/56° 33 | 36/42° 31 |
| 4,100 ft | 56/58° 28 | 57/58° 30 | 40/46° 24 |
| 3,300 ft | 58/61° 23 | 59/62° 23 | 43/50° 21 |
| 2,500 ft | 60/64° 16 | 62/65° 15 | 46/54° 15 |
| Trailhead 2,000 ft | 61/66° 14 | 64/67° 13 | 48/56° 12 |
4 more days of forecast — plan around the weather window, not just tomorrow.
Conditions synthesized from: NWS Higher Summits Forecast, NOAA Open-Meteo, Mount Washington Observatory, NETC Trip Reports, NOHRSC Snow Depth, Mt. Washington Avalanche Center, USGS Stream Levels, OpenWeather Air Quality.
AI-generated from public data. Always verify conditions before heading out — backcountry weather can change quickly.
As of July 21, 2026: South Twin Mountain (4,902 ft) is currently 51°F (feels like 42°F) with overcast and SSE winds at 14 mph, gusting to 28 mph. Today's freezing level is 13,222–14,108 ft. Expect the summit to run about 8°F colder than the trailhead. Trail conditions are rated Difficult.
Temperatures drop roughly 2.6°F per 1,000 ft of elevation on South Twin Mountain. Today the trailhead (2,000 ft) tops out around 67°F while the summit (4,902 ft) reaches about 59°F, with a wind chill as low as 54°F.
Winds at the summit of South Twin Mountain are forecast to reach 45 mph today, with 40 mph at treeline. Above treeline there is no shelter from wind — plan layers around wind chill, not air temperature.
Today's freezing level (13,222–14,108 ft) is above the 4,902 ft summit of South Twin Mountain, so the full route should stay above freezing.