891 FXUS63 KGRR 270700 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 300 AM EDT Sat Jun 27 2026 .KEY MESSAGES... - Extreme heat risk next week - Chances for showers and storms next week && .DISCUSSION... Issued at 300 AM EDT Sat Jun 27 2026 - Extreme heat risk next week Main weather concern continues to be the onset of heat and humidity after the weekend. After a comfortable weekend...hot temperatures and humidity build Monday and remain through at least the end of the week. High temperatures in the mid 90s at least can be expected with lows likely staying in at least the mid 70s. Heat index values over 100 likely Tuesday through Thursday at least with potential for 110 plus remaining...especially as you move east and south across lower Michigan. The lack of cooling at night and the expected humidity in place day and night through the week will bring extreme heat hazards to lower Michigan. Preparations should be made to mitigate the impacts of extreme heat to people and animals before the heat arrives. Heat safety tips and resources can be found by visiting: weather.gov/heat Some relief from the extreme heat may occur at the end of the week...but prolonged summer temperatures in the 80s and maybe 90s are expected to persist through at least the holiday weekend...if not through the entire first week of July. - Chances for showers and storms next week With this much heat and humidity in place it is not uncommon for us to see some afternoon/evening isolated storms or more organized activity as shortwaves move through the Great Lakes region. Best chance for showers/storms at this point still looks to be late Sunday night and Monday and again maybe the middle to the end of the week. .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 126 AM EDT Sat Jun 27 2026 Occasional MVFR at KJXN during the first 6 hours of the TAF period. Otherwise...expect VFR conditions at the terminals into Saturday night. && .MARINE... Issued at 300 AM EDT Sat Jun 27 2026 Some light morning fog may be possible through the weekend. Lights winds and waves today and again Sunday. Winds look to increase Monday with potential for hazardous winds and waves Monday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...Maczko AVIATION...Maczko MARINE...Maczko

NWS GRR Office Area Forecast Discussion