Lyons, WI Weather

This Hazardous Weather Outlook is for portions of east central Wisconsin, south central Wisconsin and southeast Wisconsin.

Day one: This Afternoon and Tonight

No hazardous weather is expected at this time.

Days two through seven: Wednesday through Monday

A few thunderstorms may occur later Wednesday night into early Thursday morning.

Spotter information statement

Spotter activation will not be needed.

Key messages

- Mild temperatures return for much of the week.

- Scattered sprinkles today then a 60-90 percent chance for rain showers late Wed night north and west of the MKE metro area. Some lingering showers Thu AM.

- Chances for rain continue each day through the weekend into early next week.

Short term

Issued 237 PM CDT Tue Oct 27 2026

Tonight through Thursday night:

A weak vortmax and upper level divergence is causing weak scattered rain over Iowa and over the upper MS Valley this afternoon. Some of this rain has clipped portions of central WI this afternoon in Sauk, Columbia, Marquette, and Green Lake Counties, while dry air has won out over other portions of the CWA.

This rain should continue to clip the same area of central WI through the rest of the afternoon, with activity waning this evening as the main forcing mechanism moves north and east. CAMs show this rain largely dissipating before trying to move into south-central and southeast WI.

Tonight following the exit of the upper level moisture, surface pressure rises and height rises aloft will support clearing skies. Skies then remain clear tomorrow. Ridging aloft and southerly winds will allow our highs to reach the low to mid 70s. Winds will be breezy, as the pressure gradient tightens ahead of an approaching low and cold front. Wednesday night, the front is expected to move overhead leading to scattered rain. A weak amount of MUCAPE from 300 to 500 J/kg is expected to be overhead with this activity, so a few rumbles of thunder will be possible with the scattered rain activity Wednesday night.

Thursday, the front should clear Wisconsin during the morning hours, with high pressure moving in behind it. Skies clear Thursday afternoon with temperatures expected to be a bit cooler in the 60s.

CMiller

Long term

Issued 236 PM CDT Tue Oct 27 2026

Friday through Tuesday:

High pressure lingers through the first half of Friday, while warm advection driven precip tries to move in from the southwest. The remaining dry air from the high should keep rain at bay most of Friday, save for in southwest WI where some may work in during the afternoon.

Model disagreement then takes hold through the remainder of the weekend as the ECMWF, GFS, and Canadian all depict different solutions. The ECMWF, generally shows rain remaining south of the border Saturday and Sunday remaining dry. The Canadian shows rain over southwest WI Saturday into the first half of Sunday, while eastern WI remains dry. Finally the GFS is the rainiest, with on and off light to moderate rain through the weekend over all of southern WI. Given this disagreement, the NBM paints broad 15 to 30% PoPs over the region through the weekend, with a fairly non- descript window of higher rain potential. With Halloween approaching and other outdoor events potentially happening this weekend, stay tuned to the forecast for better model agreement with time.

Early next week, a larger weather system does look possible, though the timing and evolution of this system remain in question given continued model disagreement beyond this weekend. Altogether, a more active pattern is expected to return.

CMiller

Aviation

Issued 132 PM CDT Tue Oct 27 2026

Remaining MVFR is slowly eroding along the Lake Michigan shoreline. These ceilings should lift to VFR through the remainder of the afternoon. Elsewhere high VFR BKN to OVC conditions exist. Some sprinkles to light rain can't be ruled out over central WI through the afternoon. High VFR cloud cover will persist into tonight with skies clearing around midnight. Skies will then remain clear Wednesday morning, with some partly cloudy skies during the afternoon.

Light to moderate southeasterly winds will become southerly and light tonight. Southerly winds then persist into tomorrow, with breezes between 15 and 20 knots tomorrow afternoon. CMiller

Marine

Issued 141 PM CDT Tue Oct 27 2026

High pressure of 30.5 inches will continue to work east across Ontario this afternoon and move over New England by Wednesday morning. Meanwhile, broad low pressure of 29.8 inches will move into the central to northern Great Plains. Moderate southeast winds will continue through this afternoon and evening, with winds remaining elevated and becoming southerly during the pre- dawn hours on Wednesday. Elevated southerlies persist Wednesday, and will become gusty Wednesday night ahead of an approaching cold front. Gusts will stop a couple knots short of gales over the northern end of Lake Michigan, though a few intermittent gusts to gale force can't be ruled out.

Winds then become southwesterly and come around to northwesterly following the front. Winds then quickly slow behind the front Thursday afternoon and evening as high pressure of 30.2 inches works in from the central plains.

CMiller

Watches, warnings and advisories

WI: None. LM: Small Craft Advisory: LMZ643-LMZ644 until 6 PM Tuesday.