Hot and humid conditions are expected to linger across parts of Wisconsin into next week, with sustained daytime highs in the 90s and overnight lows only falling into the upper 60s. Forecasters say high dew points in the 70s will combine with air temperatures to push heat index values into the upper 90s and near triple digits, prompting Heat Advisories for multiple communities.
Where advisories are in effect
Local weather services have issued Heat Advisories for several cities, with some advisories already active and others scheduled to begin tomorrow morning. The advisories are tied to the risk that combination of heat and humidity will create dangerous conditions for outdoor workers, the elderly and people with health conditions.
| City | Advisory window | Expected heat index |
|---|---|---|
| Madison | Ongoing into the week | Upper 90s |
| Eau Claire | Through Tuesday, 9 p.m. (extension possible) | Upper 90s to near 100°F |
| La Crosse | From tomorrow 11 a.m. to Tuesday 9 p.m. (extension possible) | Upper 90s to near 100°F |
| Wausau | From tomorrow 11 a.m. to Tuesday 9 p.m. (extension possible) | Upper 90s to near 100°F |
Forecast pattern and timing
A persistent ridge of high pressure is keeping hot, humid air in place, producing little relief overnight. Forecasters note that dew points in the 70s magnify the thermal stress by limiting nighttime cooling and raising relative humidity during the day, which is why heat index calculations — a measure of how hot it feels — are expected to climb into the hazardous range.
Health and safety guidance
Officials urge residents to take precautions now. Key recommended actions include:
- Stay cool indoors as much as possible and use air conditioning when available.
- Drink plenty of fluids and avoid alcohol; replace electrolytes if exercising intensely.
- Limit strenuous outdoor activity during the hottest hours, typically late morning through early evening.
- Check on neighbors, family members and anyone with chronic illness, and never leave children or pets unattended in vehicles.
Heat Advisories may be extended if temperatures and humidity remain elevated later in the week. Residents should monitor official local forecasts and mobile weather alerts for updates on timing and intensity.
Overnight temperatures will remain comparatively warm, easing only to the upper 60s in some locations, which reduces the overnight recovery period and raises cumulative heat stress through multi-day exposure.
The combination of sustained high temperatures, elevated dew points and limited nocturnal cooling is the principal driver of the advisory notices. Those with concerns about heat-related illness should contact local health services or emergency responders.
