Prohibitive cooler changes are indicated by the 12Z GFS in the Upper Midwest to Quebec in the 6-10-day period followed by much stronger cooler changes from the Midwest to the Northeast Corridor in the 11-15-day period.
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.
A broad and steadily strengthening upper trough south of Australia gradually extends a vigorous storm track northward into southern continent followed by chilly air generation leading to <32F risk in Southeast Australia and parts of southwest continent.
The first month of meteorological summer 2025 was 7th warmest on record across the U.S. MUCH ABOVE normal temperature was observed in 19 states, essentially the West U.S., Northeast States, and Florida. Rhode Island observed their 2nd hottest June on record while West Virginia, Virginia, Maryland, and Delaware ranked in the top five all-time warmest.