Extreme heat and drought have dominated headlines in recent years. But you may be surprised to know that global rainfall totals are growing over time. While totals fluctuate each year, global precipitation has increased by 0.03 inches per decade. But where—and when—during the year does rain fall on Earth?
This animated map from NASA’s Scientific Visualization Studio (SVS) explores global average precipitation by month. It relies on Integrated Multi-satellitE Retrievals for GPM (IMERG) estimates from 2001 to 2022.
The map uses a dark basemap to let the rainfall data shine. Average monthly rainfall glows bright in a range of neon colors. Blues show areas with less rain, while yellows show places with more rain. The highest totals animate in shades of orange and red.
As the video plays, you can see the monthly pulse of rain and how it moves across our planet. A nearly unbroken band of rainfall exists above the equator all year. This region is known as the intertropical convergence zone, or ITCZ. The ITCZ is associated with heavy rainfall and thunderstorms that shift north or south with the seasons. From around March to September, global rainfall appears to move north. From September to March, rain incrementally moves south. You can best see these patterns across South America, Africa, and Indonesia.
Beyond the tropics, the map also reflects other recurring trends for rainfall. In the southeastern US and Southeast Asia, hurricane and monsoon seasons manifest in greens and yellows. Japan’s rainy summers are visible. So are the wet autumns and winters along the northern Pacific coast of North America.
While the map focuses on rain, it also highlights where rain rarely falls. The negative space in regions like the Sahara and the Eurasian Steppe create inky black voids on the map. Places in southern Africa and Australia also suffer prolonged droughts between seasonal rains. The map’s simple and intuitive design makes it easy to tease out stories and patterns from 22 years of data.
More to Explore
- Visualize global water cycles since 2000.
- Discover another map of global precipitation by month.
- Watch thunderstorms move from land to water as day turns to night over Lake Victoria.
