Onalaska, WI 54650 Weather

This Hazardous Weather Outlook is for portions of southeast Minnesota: northeast Iowa and southwest into central Wisconsin.

Day one: Today and Tonight

No hazardous weather is expected at this time.

Days two through seven: Saturday through Thursday

No hazardous weather is expected at this time.

Spotter information statement

No action needed.

Emergency management coordination

No webinar is scheduled.

Key messages

- Scattered light showers over northeast Iowa and southwest Wisconsin spread northward through Halloween morning before diminishing during the afternoon and evening.

- More widespread and longer duration rainfall is expected next week (80-95%), bringing the potential to exceed 1 inch of rain (40-60%).

- Temperatures trend warmer this weekend into early next week before cooling back towards normal for the latter half of the week.

Discussion

Issued at 146 PM CDT Fri Oct 30 2026

This Afternoon - Sunday: Scattered Light Showers, Trending Warmer

Isolated to scattered showers continue across portions northeast Iowa and southwest Wisconsin this afternoon associated with an area of 925-850hPa warm air and theta-e advection. These showers should largely stay along and south of the Minnesota/Iowa border given drier air present below 10kft to the north, though can't rule out some sprinkles up to I-90 as we head into the evening. Elsewhere, cloud cover will continue to increase, but dry conditions are expected. Where showers do develop, moisture is fairly shallow so amounts should only be a few hundreths of an inch.

Light showers increase in coverage overnight as a 700-500hPa shortwave trough across Texas lifts northward atop the previously mentioned lower level forcings, coinciding with a stronger northward surge of low level moisture. While coverage will still largely be scattered, much of the Upper Mississippi River Valley should see some light rainfall through Saturday morning (50-70%), most likely across northeast Iowa and southwest Wisconsin where deeper moisture remains. Still not expecting a washout, but if some elevated instability noted in RAP soundings (100-200 J/kg) can be realized, some rumbles of thunder and localized rainfall amounts up to 0.3 inches are possible (30-50%).

The low level forcings move into northeast Wisconsin Saturday afternoon and evening, resulting in diminishing showers and some drier trick-or-treating conditions across our area. That said, can't rule out some residual light showers lingering into Sunday morning as various bits of shortwave energy slowly meander through the Upper Midwest, but mostly dry conditions should briefly return Sunday afternoon and evening. Given persistent southerly winds throughout the weekend, expect a warming trend as we head into the new week with high temperatures in the low to mid 60s by Sunday, around 10 to 20 degrees above normal.

Monday - Wednesday: Widespread Rainfall, Continued Warmth

Heading into next week, longwave troughing over the western United States moves eastward into the central Great Plains while a shortwave trough dives southward out of Canada. These features are expected to produce a fairly stout surface low pressure system that lifts northeastward into and through the Upper Midwest. At this point, it looks to be a near certainty (80-95%) that we will see rainfall across the Upper Mississippi River Valley given substantial QG forcing associated with these features.

To coincide with the forcing, an impressive northward surge of moisture is expected as the low lifts northward. The 30.00z NAEFS/EPS suggests PWATs should be above the 99th percentile of climatology, and even indicate they could be above the climatological maximum. That is to say, the atmosphere should be fairly juiced up for some efficient rainfall, but where this moisture ultimately ends up, and by association the greatest rainfall amounts, is a bit in question. The majority of the ensemble guidance (GEFS/EPS/GEPS and their AI equivalents) depict the axis of heaviest rainfall to our west closer to the current favored track of the low, but there are some members that trend the low further eastward which would result in higher rainfall amounts across our area. The 10th-90th spread of rainfall amounts in the 30.13z NBM is large at this point given the uncertainty of the low's track, but probabilities currently favor at least 1/2" (70-90%) and are fairly high for 1+" (40-60%). Otherwise, above normal temperatures continue through midweek before trending cooler behind the departing low.

Aviation

Issued at 648 PM CDT Fri Oct 30 2026

Scattered rain showers will continue through the overnight and increase in coverage early Saturday morning. These showers linger through the early afternoon and then gradually decay from the later afternoon through the evening. CIGS start out around 5000ft this evening and by early to mid Saturday morning, most locations will see MVFR CIGS between 1000 and 2500ft. These lowered CIGS remain in the area into the evening. Visibilities should remain in the MVFR to VFR range and southeast winds of 5 to 10 mph are both expected through the TAF period.

Watches, warnings and advisories

WI: None. MN: None. IA: None.