May 1 edit
2010: Record flooding began in Tennessee, eventually killing 16 people.
May 2 edit
2008: Cyclone Nargis made landfall in Myanmar, killing more than 146,000 people.
May 3: Start of National Hurricane Preparedness Week 2020 edit
1999: The second costliest tornado outbreak in history hit the area around Oklahoma City, Oklahoma, including an F5 tornado that destroyed thousands of homes and killed 36 people.
May 4 edit
2002: The Aqua weather satellite was launched into orbit.
May 5 edit
1950: Known locally as "Black Friday", heavy precipitation caused the already swollen Red River to breach several dikes, causing disastrous flooding in Winnipeg, Manitoba.
May 6 edit
1975: An F4 tornado struck Omaha, Nebraska, causing more than $1 billion (1975 USD) in damage.
May 7 edit
1840: The Great Natchez Tornado struck Natchez, Mississippi, killing at least 317 people.
May 8 edit
2009: A severe derecho blew across a large part of the United States, spawning 39 tornadoes and killing six people.
May 9 edit
1785: James Pollard Espy a prominent early meteorologist who pioneered theories of atmospheric convection, was born in Pennsylvania.
May 10 edit
1997: Maeslantkering, the largest movable storm surge barrier in the world, opened in the Nieuwe Waterweg, Netherlands.
May 11 edit
1970: Seventeen years to the day after the deadliest tornado in Texas history, another tornado struck downtown Lubbock, Texas, killing 26 people. It was the only F5 tornado in history to strike a skyscraper, which had its steel infrastructure twisted by the storm.
May 12 edit
1970: Severe floods began in Romania, eventually killing more than 200 and leaving more than 250,000 homeless.
May 13 edit
1980: A strong tornado devastated downtown Kalamazoo, Michigan.
May 14 edit
1991: The NOAA-12 weather satellite was launched into a polar orbit from Vandenberg Air Force Base, California.
May 15: Start of the East Pacific hurricane season and end of the Mauritius and Seychelles cyclone season edit
1887: A tropical storm formed southeast of Bermuda. This storm would be the first of four off-season tropical cyclones which would form in the Atlantic Ocean that year, the most in recorded history.
May 16 edit
2004: Typhoon Nida reached category 5 intensity just east of the Philippines.
May 17 edit
2003: Ratnapura, Sri Lanka, recorded 366.1 millimetres (14.41 in) of rain in just 18 hours from a tropical cyclone that caused some of the worst flooding on the island in its history.
May 18 edit
1986: Cyclone Namu, the worst tropical cyclone ever to affect the Solomon Islands, killed 150 people as it passed through the island nation.
May 19 edit
1997: A tropical cyclone made landfall near Chittagong, Bangladesh, killing more than 1,000 people.
May 20 edit
2013: An EF5 tornado struck the heart of Moore, Oklahoma, killing 24 people, including seven children at an elementary school.
May 21 edit
1953: A deadly tornado killed 2 people in Port Huron, Michigan, and crossed the St. Clair River into Canada where it killed 4 more people in Sarnia, Ontario.
May 22 edit
2011: A violent tornado killed 158 people and destroyed much of the city of Joplin, Missouri. This was the most people killed by a single tornado in the United States since the beginning of official tornado forecasts in 1950.
May 23 edit
1982: Tropical Storm Aletta reached peak intensity off the western coast of Central America. Aletta brought more than 50 inches (1,300 mm) of rain to parts of Honduras and Nicaragua, causing flooding that killed more than 300 people.
May 24 edit
2006: The GOES 13 weather satellite was launched. Part of the Geostationary Operational Environmental Satellite program, GOES 13 would provide public weather forecasting data to the United States until its retirement in 2018, when it was transferred to the United States Air Force.
May 25 edit
2009: Cyclone Aila struck Bangladesh, killing more than 300 people.
May 26 edit
1972: Subtropical Storm Alpha reached peak intensity east of Savannah, Georgia, where it would make landfall the next day.
May 27 edit
1774: Francis Beaufort, inventor of the Beaufort scale for measuring wind force, was born in Ireland.
May 28 edit
2012: Tropical Storm Beryl made landfall near Jacksonville Beach, Florida, with maximum sustained winds of 55 knots (65 mph; 100 km/h). Beryl was the strongest off-season Atlantic tropical cyclone on record to strike the United States.
May 29 edit
1995: A destructive tornado struck western Massachusetts, killing three people in the town of Great Barrington.
May 30 edit
1959: Tropical Storm Arlene made landfall near Lafayette, Louisiana, bringing more than 10 inches (25 cm) of rain to parts of the northern Gulf Coast of the United States.
May 31 edit
1889: The Johnstown Flood, caused by days of heavy rains which led to the failure of the South Fork Dam, killed more than 2,000 people in Johnstown, Pennsylvania.