Marine heatwaves, which are prolonged periods of extreme ocean temperature increases, have been occurring more frequently and with greater intensity in recent years. These heatwaves have harmful effects on ecosystems, marine industries, and human activities. Scientists use drifting buoys as one method to monitor ocean temperatures. These buoys move freely in the ocean and collect temperature data automatically, which is then relayed by satellite for immediate use in forecasts. The map displays temperature measurements from drifting buoys worldwide for the previous month.