The week-3 forecasts are cooler in the East according to most AI models and with weak MJO phase_7 and moderate -NAO there is some support for that projection. HOWEVER, during mid-summer with a vast hot air source region formed during June across the Southwest U.S., the AIFS and ECM Ensembles combine to emphasize the Southwest U.S. high pressure system entering week-3 muting an East Coast trough. CIC is siding with more impactful heat for week-3/week-4 forecasts including the Great Plains week-4.

In Europe, a worse-case scenario is unfolding. The late June heatwave core has shifted across Eastern Europe this week while beginning to regenerate in Southwest Europe/Northwest Africa (Fig. 2). In the medium range, combining GFS and ECM, the Southwest Europe heat expands and intensifies reaching U.K. days 6-10 and continues to expand eastward in the 11-15-day forecast. The hottest weather within this new heatwave expansion is across France.

The consensus of all operational models and their U.S. population weight CDD projected for the week ending July 9, 2026, is 100 CDD which would eclipse the previous hottest week of the last 10 years at 99 CDD recorded for the week ending July 23, 2022, and July 30, 2016.

Increased westerly wind in the middle latitudes is characteristic of an El Nino climate, particularly during the winter season. Increased westerlies in the middle latitude is well represented by positive phase of global atmospheric angular momentum (GLAAM) index.

Severe drought in the Mid-Atlantic region is a significant concern as July approaches. The risk of over-achieving heat is significantly elevated across a large drought area during July. The hot bias provided by extreme dry soil moisture can easily overwhelm synoptic level forecasts and that’s the concern in July for the Mid-Atlantic region. The 12Z GFS Mid-Atlantic heat is hard to ignore.