Dangerous heat likely through midweek

Here’s your Sunday evening forecast for August 20, 2023 from Minnesota’s Weather Authority and Meteorologist Matt Serwe.

Minnesota’s Weather Authority is calling Tuesday and Wednesday Forecast First Alert Days. Dangerous heat and humidity are likely both days. Record highs are possible, and it could feel like 105° or hotter both afternoons.

An Excessive Heat Warning and Heat Advisory are in effect Monday for parts of southwest and southern Minnesota. An Excessive Heat WATCH is in effect for most of southern Minnesota, including the Twin Cities metro, Tuesday through Thursday.

As you can tell from the two bolded sentences above, dangerous heat is the big story this week. Another heat dome is building through the middle of the country, and it could bring record highs to parts of Minnesota through the middle of the week. The heat begins in southern and southwest Minnesota on Monday, as highs reach the low to mid 90s, and it will feel like 105°+. In the Twin Cities Monday, it will be warmer and more humid, but it will still be tolerable.

By Tuesday and Wednesday, there will be a sharp cut-off between dangerous heat and humidity and typical late summer weather across Minnesota and northwest Wisconsin. Highs south of that line will soar into the mid and upper 90s, and the humidity will be stifling. The feels like temperatures will likely top 105° in the Twin Cities both days, making it dangerous for vulnerable groups—the very young, the very old, outdoor workers, and pets. If you are a parent, coach or administrator, the wet bulb globe temperature could be high enough to limit or cancel outdoor high school practices those days. If you are in one of those groups and do not know what I’m talking about, read the MSHSL heat safety page.

On the north side of the heat dome, there will be chances for isolated showers and storms in northern Minnesota nearly every day this week. When the ridge starts to break down by Thursday and Friday, the heat will slowly subside, and there will be a chance for storms in the Twin Cities. If you are planning ahead for the start of the Minnesota State Fair, Thursday will still be hot and humid, but the remainder of the first weekend should be beautiful.