Between the eastern entrance to the Caribbean Sea and off the northwest coast of Africa between 5N and 23N is where the tropical North Atlantic (TNA) index is calculated. The TNA is a simple SSTA value for this region which is also known as the main development region (MDR) for North Atlantic hurricanes. In May, the TNA index declined -0.50 to -0.18, the strongest negative monthly drop in the 1950-2021 climatology.

U.S. rankings for temperature and precipitation were almost exactly in the middle of the 127-year climatology. However, as is often the case, normal (nationally) can be the average of extremes.

Rainfall required to neutralize dry Palmer Drought Severity Index (PDSI) has increased dramatically during early June in the East U.S. Already steep departures across the West U.S. have also worsened. The California and Washington/Oregon (along the Cascades) rainfall deficits are off-the-chart >15 in.

The Climate Impact Company North Atlantic tropical cyclone season forecast of seasonal activity for 2021 is updated. The seasonal forecast activity is lowered slightly although the number of intense hurricanes increases from 2 to 3. The ACE index lowers sharply to 106 (from 127).