The official U.S. population weight CDD for August 2025 from NOAA will be published in a few days. Climate Impact Company (CIC) projects 272 CDD for August which is cooler than the 30-year normal (290 CDD) and much cooler than the 10-year normal (332 CDD). The NOAA assessment is (more) likely cooler than the CIC estimate. The AUG-25 CDD total is 2nd coolest (for AUG) this century trailing only 2004 (254 CDD).

The strongest marine heat waves (MHW) on record in the West Pacific and in-between Japan and the Asia Coast extending to MHW’s NEP25A and NEP25B in the Northeast Pacific are well-correlated to the summer 2025 upper air pattern featuring a strong upper-level high-pressure ridge. Similarly, the MHW’s in the east/northeast portion of the North Atlantic are well-correlated to a semi-permanent upper-level high-pressure ridge dominating the west/south portion of Europe during summer 2025.

The lack of tropical cyclone activity across the Gulf of Mexico and Caribbean Sea is allowing each basin to shift warmer. The Gulf of Mexico is nearly 1C warmer than normal and warmer by 1/3C during the past 30 days. The Caribbean Sea has warmed by 2/10C during the past 30 days to 0.65C. However, the North Atlantic basin is marginally warm at +0.34C and much cooler than 1 year ago by 0.52C.

The Climate Impact Company constructed analog climate outlooks for meteorological spring 2025 and winter 2025-26 is issued. The spring season is mostly cooler than normal across much of the continent with a wet bias in the East. The summer outlook reverses drier and hotter in the East.