During the past 1-2 weeks, the Nino34 SSTA has cooled by more than 0.4C to -0.28C in the latest daily analysis. The La Nina threshold is -0.5C. Running parallel (and possibly related) to the Nino34 SSTA cooling is the vivid cool SSTA off the U.S. West Coast with that cooler water riding the California Ocean Current south and southwestward toward the tropics.

On July 1st, the AIFS ENS is introduced to operational weather forecasts. The 6-10-day 2-meter temperature forecasts for regions of the U.S. indicate a skill consensus score that ranks the debut of AIFS ENS at number 1 with AIFS a close second and the routinely top dynamic model, ECM ENS, at number 3.

Dynamic and AI forecast models are shifting an upper trough into the East during the week 2-3 ahead period. CFS V2 lingers the trough in week-4 while ECM and AI models regenerate a Northeast U.S. ridge at that time. Climate Impact Company recognizes optimum climate normal (OCN) when potential pattern change is forecast in the extended range.

The Climate Impact Company U.S. selected cities CDD forecast shifted hotter in this week’s update and is close to the 2022 and 2024 observations. Summer of 2022 ranked 3rd hottest on record for the U.S. while summer 2024 ranked 4th hottest. The observed summer 2025 CDD will rival the 2022 and 2024 heat primarily due to the anomalous heat observed in the PJM sector.