MOUNTWASHINGTON.COM: Weather: Extremes

	M O U N T W A S H I N G T O N . C O M
	Weather

Notorious for its frequent bad weather conditions, Mount Washington's climate can rival that of Antarctica. Well over a hundred people have died on the mountain, many having succumbed to hypothermia from wind chills which have been known to reach -120°F. And it was here, on the roof of what is now the Stage Office, where the world's highest wind speed was recorded: 231 MPH.

The average annual temperature on the summit is only 26.5°F, with the records being -47°F and 72°F. On average, 256 inches of snow falls annually, with the seasonal maximum being 566 inches. Even months like May have seen around 100 inches! Mt. Washington's mean wind speed is a gale-force 35.3 MPH, with hurricane-force winds occurring every third day (on average).

Visitors often wonder at photos of the summit during wintertime, when every building, tower, post, and rock is caked in a thick, snow-like frosting of "sideways icicles". It isn't snow at all! It is rime ice, which is formed when supercooled (liquid) fog particles crash into the windward side of things. Due to sub-freezing temperatures and high winds, the particles freeze on contact and create the feathery ice formations. With the summit in dense fog 60% of the time, tremendous rime buildup often occurs.



Heavy rime ice encases the Stage Office.		This looks more like a scene from The Shining!
One of the many warning signs up on the mount		You don't have to read it to get the picture...

Rescue cache itself caught in major avalanche		Mangled forests attest to the extreme winds.

Cog Railway destroyed by 162mph winds		Wooden cross where two men froze to death

Digging out the front porch... in JUNE!		A powerful blizzard leaves the staff snowbound.

Fun weather every month of the year!

Jan. 14, 2004:
-45°F air temperature and winds over 100 MPH make it feel almost like absolute zero! Feb. ?, 1969:
The mountain gets 49.3" of snow in a 24-hour period, and 172.8" for the month! Mar. 6, 1997:
Adam enjoys an arctic trip to the summit, under a Blizzard Warning and 131 MPH winds. Apr. 12, 1934:
Observers record 231 MPH winds, setting a new world record which stands undefeated today!

May 26, 1997:
Memorable Memorial Day! Several feet of snow and 10' high drifts still bury the summit. Jun. ?, 1975:
Temperatures hit a "balmy" low of 8°F. Jul. 20, 1996:
Fog and drizzle turned evil when the summit clocked a new record wind speed for July, 154 MPH. Aug. ?, 1965:
Winter decides to pay a visit smack in the middle of summer, dumping a few inches of snow on the summit!

Sep. 21, 1938:
Though winds have peeled the roofs off of Cog Railway trains before, today's 162 MPH wind destroyed the entire Jacob's Ladder trestle! Oct. 20, 1996:
Freezing rain encases Mt. Washington in 10.83" of solid blue ice. Ice skating, anyone? Nov. 5, 2004:
Winter blows in on 145 MPH winds. Nice autumn air: 12°F, light snow, freezing fog, zero visibility... Dec. ?, 1933:
Temperatures hit a mercury-freezing -46°F.

[ANEMOMETER] Windy Facts: [WIND VANE]

• Mt. Washington holds the world record for wind speed: 231mph!
• This was recorded on April 12, 1934 atop the old Observatory.
• Hurricane-force winds occur, on average, 104 days per year.
• In winter, though, this typically occurs 3 out of every 4 days!
• Also in winter, 100mph winds usually occur every 3 days.

Graphics ©1999 by Adam R. Jones