In the Mid-Atlantic region, a Flood Watch is issued for excessive rainfall and severe storm threat for today. In high population centers of Washington, Baltimore, and Philadelphia dangerous flash flooding is possible late today/tonight!

Sneaky chilly weather into Southern Brazil this morning and Wednesday morning with moderation to follow later this week. Next week, ECM projects a warmer regime across Argentina and Brazil. However, AI 4Cast Net V2 ECM ENS regenerates chilly weather. An important ECM Vs. AI test case for Brazil next week!

A warmer change in the 11-15-day forecast as ECM ENS loses the cool regime into early next week and rewarms much of the U.S. including hot weather extending from California to the Mid-south States. Note the wet arc across Cuba possibly related to a tropical system.

The U.S. population weight CDD forecast reveals the current week as hottest (nationally) of summer 2025 (Fig. 1). Previously, 2 spike hot week regimes were observed ending 6/26 and 7/17. Projected as the 3rd hottest week of summer 2025 is the week ending 8/14.