structural:summarization, information:classification
Wind

The Golden Gate Bridge was designed to safely withstand winds of up to 68 mph (109 km/h). Until 2008, the bridge was closed because of weather conditions only three times: on December 1, 1951, because of gusts of 69 mph (111 km/h); on December 23, 1982, because of winds of 70 mph (113 km/h); and on December 3, 1983, because of wind gusts of 75 mph (121 km/h). An anemometer placed midway between the two towers on the west side of the bridge has been used to measure wind speeds. Another anemometer was placed on one of the towers.

As part of the retrofitting of the bridge and installation of the suicide barrier, starting in 2019 the railings on the west side of the pedestrian walkway were replaced with thinner, more flexible slats in order to improve the bridge's aerodynamic tolerance of high wind to 100 mph (161 km/h). Starting in June 2020, reports were received of a loud hum, heard across San Francisco and Marin County, produced by the new railing slats when a strong west wind was blowing. The sound had been predicted from wind tunnel tests, but not included in the environmental impact report; ways of ameliorating it are being considered. An independent engineering analysis of a 2020 sound recording of the tones concludes that the singing noise comprises a variety of Aeolian tones (the sound produced by air flowing past a sharp edge), arising in this case from the ambient wind blowing across metal slats of the newly installed sidewalk railings. The tones observed were frequencies of 354, 398, 439 and 481 Hz, corresponding to the musical notes F, G, A, and B; these notes form an F Lydian Tetrachord.