textproduct: Grand Rapids

KEY MESSAGES

- Heat wave begins Monday, continues through at least Thursday

- Chances for showers and storms

DISCUSSION

Issued at 244 AM EDT Sun Jun 28 2026

- Heat wave begins Monday, continues through at least Thursday

Heat and humidity begin building in Monday with hot and humid conditions continuing into the end of the week. Hottest days continue to be Tuesday, Wednesday and Thursday when highs will be in the mid to upper 90s and heat index values will be well into the 100s.

Monday may not be a slam dunk criteria Heat Warning day for all of the area as lingering clouds and slow building heat may limit temperatures especially the further north you go. In spite of that and maybe being a few degrees into Advisory vs Warning guidance numbers here or there...the significant impacts of a prolonged heat and humidity stretch (4 days or more) warrant the issuance of an Extreme Heat Watch for Monday through Thursday that is likely to become an Extreme Heat Warning sometime within the next 24 hours.

Anything that can be done to prepare for the heat and humidity should be completed by today as the heat begins Monday. This would include modifying scope and duration of planned outdoor activities this week and taking extra precautions for animals and vulnerable populations among other things.

While some relief from the extreme heat may occur after Thursday...hot and humid conditions are expected to persist through at least the 4th of July holiday weekend and possible much of the week after.

- Chances for showers and storms

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 the middle to the end of the week though models continue to show limited support for showers/storms.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 147 AM EDT Sun Jun 28 2026

VFR conditions expected through the period. A few light showers may move into the region from the west near or after 00z...but these should be pretty light and are currently not expected to impact VFR condition. Winds will be light out of the east for the first six hours or so of the TAF period before shifting to be out of the southeast.

MARINE

Issued at 244 AM EDT Sun Jun 28 2026

Sunday will feature light easterly to southeasterly winds. Monday sees the return of the risk for hazardous waves that probably will continue through Tuesday. Small Craft Advisories and Beach Hazards Statements are looking more likely for both Monday and Tuesday. Those looking to seek relief from the heat Monday and Tuesday should be aware that hazardous waves and currents are likely to be encountered in Lake Michigan.

GRR WATCHES/WARNINGS/ADVISORIES

MI...Extreme Heat Watch from Monday afternoon through Thursday evening for MIZ037>040-043>046-050>052-056>059-064>067- 071>074. MARINE...None.