National Big Wind Day Date in the current year: April 12, 2026

Wind is the movement of air from regions of higher atmospheric pressure to regions of lower atmospheric pressure. These differences in pressure are primarily caused by temperature differences. The movement of air is also affected by the Earth’s rotation, known as the Coriolis effect, as well as topographic differences, such as mountains and valleys.

Wind speed is one of the most fundamental quantities in meteorology. Wind speed affects weather forecasting, maritime operations, aviation, construction projects, agriculture, and more. The meter per second, the SI unit for velocity, is the recommended unit for reporting wind speeds. However, historical reasons may necessitate the use of other units, including kilometers per hour, miles per hour, feet per second, and knots (nautical miles per hour).

Wind speed and direction are measured using a device called an anemometer, invented in the mid-15th century. The most common type is the cup anemometer, which has three or four cups mounted on horizontal arms. As wind blows, it causes the cups to rotate. The rotation rate is proportional to the wind speed and is converted into a numerical value. Other types include vane anemometers, hot-wire anemometers, laser Doppler anemometers, and ultrasonic anemometers. A historic wind gust was recorded at Mount Washington using a hot-wire anemometer.

Mount Washington, the highest peak in the Northeastern United States, is located in New Hampshire and is notorious for its erratic weather. Founded in 1932, the Mount Washington Observatory has even been dubbed the “Home of the World's Worst Weather” and is widely known for recording the highest wind speed in the world in 1934, a record that stood until 1996.

On April 12, 1934, the observatory staff recorded a wind gust of 231 mph (approximately 372 km/h) at the summit of Mount Washington using a hot-wire anemometer designed specifically for that location. The National Weather Bureau later tested the anemometer and confirmed its accuracy.

This wind gust became known as the Big Wind. It remained the highest wind speed ever recorded until April 10, 1996, when it was surpassed by a gust of 253 mph (408 km/h) recorded by an automatic weather station on Barrow Island in Australia during the passage of Cyclone Olivia. Nevertheless, the Big Wind remains the highest surface-level natural wind gust in the Northern Hemisphere and the world’s highest measured wind speed not associated with a tornado or tropical cyclone.

Although it's unclear who first came up with the idea to celebrate the anniversary of the record-breaking wind at Mount Washington, National Big Wind Day is a great opportunity to learn more about meteorology. If the weather permits, you can celebrate by flying a kite, sailing, windsurfing, or paragliding.