Weather

 

MWObs Higher Summits Forecast
NWS Higher Summits Forecast

The climate on Mount Washington and the Presidential Range can rival the severity of the greatest ranges in the world. Arctic temperatures, hurricane-force winds, snow and icing are possible in any month. Mt. Washington’s weather can challenge the best mountaineers and, particularly during winter months, it can have climatic conditions that forbid travel on the mountain. Having the right equipment, knowing your limits and turning around before pushing it too far in wild weather are very important to the safety of your trip. Mount Washington is the highest summit in the Presidential Range (6,288 feet/1917 meters) and the highest peak in the northeastern United States, and it has earned itself a fierce reputation. Be prepared for extreme wind, precipitation, and cold throughout the year.

The winds

The Presidential Range is probably most well known for its winds. Wind velocity on Mount Washington averages 32mph (57km/h) year-round. At nearby lowland stations, the average wind velocity generally ranges from 6.5-13 km/h. Hurricane force winds (> 121km/h) are observed from the summit of the mountain on average of 110 days per year. From November to April, hurricane force winds occur on average of 2 out of every 3 days. Winds of 161 km/h or greater occur about every 3rd day from November through March. In January, the windiest month, the winds reach or exceed hurricane force on 3 out of every 4 days. On January 2nd, 1969, the winds averaged 161km/h for 24 hours, with a peak gust of 241 km/h. In winter, conditions of this type are fairly common on Mount Washington. In addition, Mount Washington holds the world’s record wind speed ever recorded from a surface weather station. In April 1934, observers measured a 371km/h wind gust before the anemometer was destroyed.

The rain and snow

Snow falls on Mount Washington every month of the year. As one would expect, frequency and amount of precipitation increase with elevation. Yearly snowfall on the summit of Mount Washington averages 645 cm. Average annual snowfall at lowland stations in the area is about 287 cm. On average, at least 2.5 cm of snow falls 68 days a year (the radar image below is of a major Nor’easter). The snowiest winter on record was 1968-69, when 1438 cm fell on Mount Washington. Snow depth measurements from the Mount Washington Observatory on the summit are somewhat uncertain, as snow often blows away as soon as it begins to accumulate, and snowfall is blown over the summit of Mount Washington from other areas of the mountain.

Nor'Eastern over Mount Washington

The pervasive high winds move large quantities of snow off the upper elevations, resulting in incredible wind loading events for the avalanche starting zones along the flanks and ravines of the range. Wind-blown snow is a major contributor to large avalanche cycles in the range. Snow depths on the floor of Tuckerman Ravine on the lee side of Mount Washington average 12 to 16 m.

The Presidential Range is located within 160 km of the Atlantic Ocean. Rain events are not uncommon during the winter months. Total average precipitation on Mount Washington is 252 cm. Precipitation levels in the lowlands around the range (610 m. elevation) average 117 cm in a year.

On average, Mount Washington is shrouded in dense fog and clouds 315 days each year.

The cold

The commonly low temperatures recorded in the Presidential Range often catch the unwary visitor by surprise. Exposure is the second highest cause of fatalities in the range, overshadowed only by falls in steep terrain.

The temperature on the summit of Mount Washington is significantly colder than the surrounding lowlands. The record high for the summit is 23 degrees C. The lowest temperature ever recorded was -45 C. July is the warmest month of the year with an average of only 9 C. February is the coldest, averaging only –15 C. Freezing temperatures are recorded 243 days during an average year. Temperatures drop to below –18 C on an average of 66 days, and reach or exceed 15 degrees C on only 19 days a year. One of the results of such cold temperatures is permafrost at 6 m deep year-round.

The high winds and brutally cold temperatures frequently arrive together. The coldest periods on Mount Washington arrive on northwest winds. Temperatures of –35 C and winds in excess of 160 km/h are not uncommon in winter.

Trip Preparation

Obtaining the latest weather information is critical to the success of your trip and the safety of your party. Climbers, skiers, riders and the other visitors who plan on traveling in avalanche terrain can use the weather information in the following links as well as the latest Avalanche Advisory to obtain critical information regarding current and future snow stability. For more information about the weather on Mount Washington and avalanche conditions on Mount Washington, take some time to read Avalanche Terrain and Conditions in the Presidential Range, from which much of the above weather discussion is drawn.

The Mount Washington Avalanche Center gathers weather information from a variety of sources. We find that no one source gives us a complete picture of what has happened and what will happen with the weather. The links below are some of our most commonly used sources of information. For those of you who really want to delve deeply into amateur meteorology, we’re including some links to sites that can keep you occupied for a long time.
Mount Washington Observatory:
Weather Home Page
Current Summit Conditions
Weather Report
Higher Summits Forecast
Mount Washington Valley Forecast
Auto Road Vertical Temperature Profile (Current Temperatures at Various Elevations)

National Weather Service:
NWS Regional Office (Portland Maine) Home Page
Radar Images of the Northeastern United States
Latest Regional Weather Summary from the National Weather Service
National Weather Service Current Conditions for Mount Washington
NWS Higher Summits Forecast

New Hampshire Doppler Radar Loop from Intellicast.com

Educational Sites:

TheWeatherPredicition.com
This is an easy-to-navigate site devoted to providing basic to advanced information for those interested in weather forecasting.

Unisys Weather
Provides a complete source of graphical weather information intended to satisfy the needs of the weather professional, but can be a tool for the casual user as well. The graphics and data are displayed as a meteorologist would expect to see. For the novice user, there are detailed explanation pages to guide you through the various plots, charts and images.

Meteorology Education and Training
Established to provide education and training resources to benefit the operational forecaster community, university atmospheric scientists and students, and anyone interested in learning more about meteorology and weather forecasting topics. The site houses online learning materials, as well as information on other training and education activities, such as classroom courses, tele-training and links to other related resources.