Hot and gusty conditions will give way to a more uncertain and potentially dangerous Monday across parts of the Upper Midwest, forecasters say. A southerly flow is set to push warm air north on Sunday, producing widespread daytime highs in the 80s and periods of strong winds ahead of a weather system that could trigger severe thunderstorms.
What to expect Sunday into Monday
Sunday will finish warm and largely sunny, with gusts above 30 mph in places as winds draw heat from the south. Temperatures are expected to reach the upper 80s to low 90s in eastern North Dakota and into the mid-80s across parts of western Minnesota. Smoke from distant wildfires may drift into eastern North Dakota but air quality is anticipated to remain acceptable.
That milder, blustery air will be followed by a frontal system that increases the chance of showers and thunderstorms overnight and into Monday. Forecasters have declared a First Alert Weather Day for Monday, reflecting the potential for organised storm activity that could become severe in places.
Severe threat and primary hazards
The greatest concerns with any storms that develop are:
- Large hail — isolated storms could produce hail up to around quarter-size, while a later round of storms carries the potential for even larger stones described as roughly ping-pong ball-sized.
- Damaging straight-line winds — gusts associated with severe cells could reach up to 70 mph in the most intense storms.
- Isolated tornado — while not the main threat, a brief tornado cannot be ruled out if conditions become locally favourable.
Forecast confidence varies through the event; the risk is described as conditional, which means severe outcomes depend on how storms initiate and interact during the day. The National Weather Service and local broadcasters advise keeping a close watch on updates.
| Area | Short-term Sunday | Monday threat |
|---|---|---|
| Eastern North Dakota | Upper 80s–low 90s; gusts >30 mph | Isolated to scattered severe storms; hail & winds |
| Western Minnesota | Mid-80s; breezy | Level 2 risk in NW MN / Red River Valley later Monday |
Timing and geography
An initial batch of showers is likely to move in during the overnight hours into early Monday, potentially producing scattered storms in the morning. A more vigorous round in the afternoon and evening carries the stronger severe threat, particularly across the Red River Valley and northwest Minnesota where a higher (Level 2) risk has been indicated. Eastern North Dakota is included in a lower (Level 1) risk for later in the day, meaning isolated to scattered severe storms are possible there as well.
Where storms do not materialise, Monday will still be a warm, mostly cloudy day with highs in the 80s. Cooler air is expected to follow the system: by Tuesday mornings values should fall into the 50s, with daytime highs rebounding into the mid-70s — the coolest readings of the week.
Practical advice
With the event conditional but capable of being disruptive, residents and outdoor planners across the risk area should:
- Keep a reliable weather app, NOAA or local broadcaster channel to receive timely watches and warnings;
- Have a plan to move indoors quickly if severe thunderstorm warnings are issued — hail and 70 mph winds can damage vehicles, roofs and trees;
- Secure loose outdoor items and be mindful of potential power cuts if winds or falling branches occur.
In short, enjoy the late-summer warmth on Sunday but remain alert: Monday brings a real, if conditional, severe-weather threat that could produce large hail, damaging winds and isolated tornadoes. Stay tuned to updates as the situation evolves.
