Mount Washington, New Hampshire: The Most Extreme Weather Observatory on Earth

Located in the White Mountains of northern New Hampshire at 6,288 feet, the observatory features some of the world's most fascinating weather.

The history of Mt. Washington Observatory began all the way back in 1870. In hopes of improving forecast knowledge, a group of determined scientists set out on an expedition to observe Mt. Washington's winter weather.

The team's observations captured the attention of the United States Signal Service, a precursor to the National Weather Service, who decided to take up the cause and maintain a weather station at Mt. Washington's summit until 1892. This was one of the first mountaintop weather stations in the world.

On Oct. 15, 1932, a group of civilians founded the modern-day Mt. Washington Observatory and continued the work of the United States Signal Service. Meteorologists and researchers continue learning more about our atmosphere each day from their work at the summit of Mt. Washington. The observatory is a non-profit organization dependent on donors.

Weather observations and forecasts at Mt. Washington Observatory are compiled by a human weather observer who goes outside to brave the dangerous elements.

(MORE: See Current Summit Conditions | Five-Day Forecast)

Wind speeds are measured by an anemometer (a pitot tube) and the observer pulls the value off the computer – this is one observation that is technically done indoors, though the anemometer itself, of course, is outdoors.

The warmest temperature ever recorded at the summit of Mt. Washington is 72 degrees, which occurred in both August 1975 and June 2003. For comparison, Berlin, New Hampshire, less than 30 miles to the north of Mt. Washington and over 5,200 feet lower in elevation, has reached 98 degrees on two separate occasions.

The only months of the year Mt. Washington has not recorded a below-zero temperature are June, July, August and September. In fact, in July, the warmest time of the year for much of the Northeast, temperatures have dipped as low as 24 degrees on Mt. Washington. This occurred in July 2001.

(MORE: July is the Warmest Time of the Year for Much of the U.S.)

On the other end of the spectrum, the Mt. Washington Observatory has been as cold as 47 degrees below zero in January 1934. The persistent strong winds atop Mt. Washington keep temperatures from reaching 50 below zero or colder in the winter, but the wind chill certainly makes up for it.

Speaking of strong winds, Mt. Washington observed a wind gust as high as 231 mph in April 1934. This would be equivalent to an EF5 tornado (200-plus mph) or a Category 5 hurricane (157-plus mph), the highest rating of each. On average, the windiest month is January, with an average wind speed of 46 mph, which is still equivalent to tropical storm force. Even during the calmest month, August, wind speeds still average around 24 mph.

A former intern at Mt. Washington Observatory, Samuel Hewitt, told weather.com, "In January 2014, I experienced 120-mph winds in 26 degrees below-zero temperatures, which equates to a wind chill of roughly 80 degrees below zero. I got frostbite on the tip of my nose in less than 30 seconds."

As expected, snow and ice are common up at 6,288 feet. Measurable snow has been recorded in each month of the year at Mt. Washington Observatory. Even in the summer, July averages a trace of snow and August averages 0.1 inches of snow. In fact, 1.1 inches of snow was measured atop Mt. Washington in July 1957, and 2.5 inches was measured in August 1965.

(MORE: When the First Snow of the Season Typically Falls)

The average snowiest month at Mt. Washington is December, with an average of 45.5 inches of snow. However, the snowiest month on record is February 1969 when 172.8 inches of snow fell. Also during that month, 49.3 inches of snow fell within 24 hours, making it the highest 24-hour snowfall total on record at the summit.

Mt. Washington's snowiest winter was 1968-69 when 566.4 inches fell, including the 172.8 inches in February 1969, as referenced above. However, not all of that was pure snow, as ice pellets (sleet) and hail are also a common occurrence at the observatory.

If you're interested in getting a taste of some of this extreme weather, guided tours of Mt. Washington Observatory are open to the public. The weather station is staffed 24 hours a day, 365 days a year, so a weather observer is always there to experience the incredibly unique weather at the summit.

MORE ON WEATHER.COM: Mt. Washington Photos