160 FXUS21 KWNC 241806 PMDTHR US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM EDT June 24 2026 SYNOPSIS: Leading up to and through the July 4th holiday, persistent extreme heat is the primary hazards concern for many areas of the contiguous U.S. (CONUS) east of the Rockies. Strong mid-level high pressure is forecast to persist from the end of week-1 into week-2 across the eastern CONUS at the beginning of week-2, shifting to central CONUS by the middle of the period, bringing increased likelihood of extreme heat for these areas. Multiple models indicate stronger mid-level high pressure compared to yesterday translating to greater heat signals. Therefore, the risks of extreme heat have been expanded in today's outlook. High risk of extreme heat is designated for parts of the eastern CONUS at the beginning of the period, with broader areas of slight and moderate risk east of the Rockies until the middle of week-2. Anticipated high dewpoints would promote heat index values exceeding 100 to 105 deg F in many areas with warm nights in the 70s-80s likely limiting overnight relief. A possible tight pressure gradient may result in episodic high winds across some coastal portions of northern California and southwestern Oregon. HAZARDS High risk of extreme heat for parts of the Mid-Atlantic and Southeastern U.S., Thu-Sat, Jul 2-4. High risk of extreme heat for portions of the Middle Mississippi, Ohio, and Tennessee Valleys, and Great Lakes region, Thu-Fri, Jul 2-3. Moderate risk of extreme heat for much of the central and eastern CONUS, excluding higher elevation areas in the Appalachians, Thu-Sat, Jul 2-4. Slight risk of extreme heat for much of the central and eastern CONUS, Thu-Sun, Jul 2-5. Slight risk of high winds for coastal portions of northern California and southwestern Oregon, Thu-Sat, Jul 2-4. DETAILED SUMMARY FOR SATURDAY JUNE 27 - WEDNESDAY JULY 01: https://www.wpc.ncep.noaa.gov/threats/threats.php FOR THURSDAY JULY 02 - WEDNESDAY JULY 08: Persistent extreme heat continuing from week-1 into week-2 heading into and through the July 4th holiday continues to be the primary hazards concern. Multiple model ensemble means indicate increased strength of an amplified mid-level high pressure compared to yesterday. At the beginning of the period, ridging is anticipated to be centered across the southeastern CONUS, with a mean maximum 500 hPa heights of 595 dam, retrograding to the central CONUS by mid week-2. Mid-level troughing is anticipated to develop across the East Coast by the latter part of the period (around day 11, Jul 5) which could provide some relief in heat-affected areas in the East. Due to increasing heat signals, the areas highlighted with risk of extreme heat have been expanded spatially relative to yesterday's forecast. A high risk (>60% chance) of extreme heat is posted for the Mid-Atlantic and Southeastern U.S., Jul 2-4, with the addition of the Middle Mississippi, Ohio, and Tennessee Valleys, and Great Lakes region, Jul 2-3. A broad area of moderate risk (40-60% chance) is highlighted across much of the central and eastern CONUS, excluding higher elevation areas in the Appalachians, Jul 2-4. An even larger area is designated with a slight risk (20-40% chance) across many areas east of the Rockies, Jul 2-5. High humidity is anticipated to amplify heat index values in many of the hazardous heat areas. Various heat tools show elevated probabilities across the designated moderate and high risk areas, with heat index values possibly exceeding 100-105 deg F in many areas. The National Blend of Models (NBM) indicates possible near or record breaking daytime temperatures across parts of the East including coastal areas. An even more widespread area is indicated in the NBM for possible record high nighttime temperatures in the upper 70s to lower 80s deg F limiting nighttime relief. Another key consideration is the Nation's 250th Anniversary this July 4th, with lots of outdoor activities planned. Staying hydrated and limiting exposure to very hot, humid weather is very important, especially vulnerable populations including older adults. Possible surface lows across the West with adjacent surface high pressure over the Northeastern Pacific may result in a tight pressure gradient across parts of the West Coast. A slight risk of high winds is designated for coastal portions of northern California and southwestern Oregon Jul 2-4. Further south, a center of 500 hPa heights exceeding 594 dm is indicated by multiple ensemble means across eastern portions of the Four Corners region during week-2 which would be favorable for monsoonal moisture advection into the Desert Southwest. PETs show some parts of the very southern portion of Arizona having 3-day rainfall totals exceeding 0.5 inches. The risk over this area is still limited at this time precluding a heavy precipitation hazard from being designated at this time but will be monitored closely in the upcoming days. Recent deterministic models indicate the increased potential of localized heavy rainfall in parts of the Four Corners region, with thunderstorms possible. FORECASTER: Melissa Ou $$