December 15 edit
1968: The ESSA-8 weather satellite was launched.
1999: Intense rains in the Venezuelan state of Vargas caused extreme landslides and debris flows which continued into the next day, destroying entire towns and killing tens of thousands of people.
1999: Cyclone John made landfall near Whim Creek, Western Australia, with wind gusts measured as high as 210 km/h (130 mph) but relatively little damage reported.
2016: The first satellite of the Cyclone Global Navigation Satellite System, a multi-satellite project using GPS signals to probe the inner workings of the atmosphere and ocean within tropical cyclones, was launched.
2021: A major severe weather outbreak struck the Central United States, including a derecho with winds up to 100 miles per hour (160 km/h) and 120 tornadoes—the most ever recorded in an outbreak in the month of December.