Janesville, WI 53501 Weather

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

Day one: Today and Tonight

No hazardous weather is expected at this time.

Days two through seven: Saturday through Wednesday

No hazardous weather is expected at this time.

Spotter information statement

Spotter activation will not be needed.

Key messages

- Dry fall morning and early afternoon today, but sprinkles and light shower chances increase from southwest to northeast later this afternoon and evening.

- Light rain chances (40-70%) continue this evening through Saturday morning/afternoon Rain chances then decrease Saturday evening.

- Additional shower chances early next week.

Update

Issued 640 AM CDT Fri Oct 30 2026

More fall-like conditions today with the crisp morning temps only warming into the 50s through the day. Winds will become more onshore off of Lake Michigan as high pressure works its way across the Upper Great Lakes this afternoon/evening resulting in extra moisture for southern WI. Meanwhile, will see low- level WAA and cloud cover spread in from the southwest to the northeast with a mid-level ripple. The moisture paired with increased low-level forcing should be enough to support increase sprinkles and light shower chances as these feature lift into southern WI. I did lean more on some aggressive models and earlier arrival of precip such as the ARW bringing in sprinkle chances in as early as 18-21z for southern portions of the CWA, with light showers and better accumulations for the late afternoon and evening. Initial precip looks to be more patchy to scattered in nature. However, better coverage and increased chances (50-85%) are likely overnight into Saturday morning lingering into the afternoon. Then the forcing is progged to lift north followed by drier conditions for Saturday later afternoon and evening.

Wagner

Short term

Issued 1114 PM CDT Thu Oct 29 2026

Today (Friday) through Saturday night:

High pressure remains in place through today, gradually sliding eastward as low pressure develops in the central Plains. Expect early morning lows in the mid to upper 30s away from Lake Michigan, with patchy fog and frost in low-lying areas. Light and variable to calm winds expected through much of the day, becoming east-southeasterly as low pressure lifts gradually northward and warm frontogenesis develops across southern Wisconsin. High temperatures in the upper 50s to perhaps 60 degrees in the afternoon.

As warm frontogenesis begins to dominate the weather pattern this evening, expect scattered showers to spread west to east along and south of I-94. Very minimal MUCAPE around 150 J/kg near the WI/IL border may allow for an isolated bolt of lightning, but probabilities are very low (less than 10%). Overnight lows expected to remain in the 40s with plenty of cloud cover and increasing humidity. Rain showers will spread northward through the remainder of southern Wisconsin into early Saturday morning, gradually becoming more scattered to isolated as low pressure propagates northward and frontogenesis weakens across the region. With winds shifting to southeasterly and becoming breezy, expect highs in the upper 50s to low 60s even with plenty of cloud cover.

Last of the showers exit to the north into Saturday night, with winds becoming light and variable. Lows in the mid 40s expected.

MH

Long term

Issued 1114 PM CDT Thu Oct 29 2026

Sunday through Friday:

Ridging remaining across Lake Michigan will keep the majority of southern Wisconsin dry on Sunday, with some potential for isolated showers with lingering moisture and WAA in the vicinity. Highs in the 60s are expected. Low pressure in the Plains deepens Sunday night as additional troughing propagates eastward over the Rockies and interacts with the surface low in the vicinity. This will lead to increasing southerly winds into Monday morning, leading to continued highs in the upper 60s. As low pressure deepens throughout Monday, it will eject into the northern Plains, bringing increasing rain chances (50-80%) to southern Wisconsin within the WAA region of the low. Low pressure continues to propagate northeastward into Minnesota by Tuesday morning, keeping southern Wisconsin within the WAA region and bringing continued rounds of rainfall (60-80% chances) throughout Monday night into Tuesday.

Uncertainty remains in the strength of low pressure, with the Euro indicating a stronger low and the GFS and Canadian indicating a stronger Northeast U.S. high preventing low pressure from continuing to propagate eastward and weakening its impacts. Regardless of exact model solution, precipitation will continue across southern Wisconsin along the occluded front of this system through Tuesday into Tuesday night as the low propagates into western Ontario (40-60% chances precipitation through the period). A transition to the cold frontal feature of this system occurs Wednesday, bringing an end to highs in the 60s by Thursday and a return to highs in the 50s. With this cold front in the vicinity into Thursday, continued shower and storm potential may also linger (20-35%).

A cold high pressure system sliding southward through the Canadian Prairies will bring a return to northwesterly winds, dry conditions, and highs in the low 50s by Friday.

MH

Aviation

Issued 640 AM CDT Fri Oct 30 2026

Mostly VFR conditions expected through the period for southern WI. High clouds are spreading in this morning with light and variable winds, but mid-level clouds and more easterly winds are progged to filter in through the afternoon as the high pressure works its way across the region. With easterly flow and low- level WAA spreading into the area through the afternoon and evening, did lean more into the early arrival of patchy to scattered sprinkles and light showers later this afternoon and evening. Then more widespread and persistent light showers overnight lingering through Saturday morning with more southeasterly winds. May see pockets of MVFR ceilings and visibility moreso with this round of activity.

Wagner

Marine

Issued 1114 PM CDT Thu Oct 29 2026

High pressure around 30.2 inches will gradually slide eastward from northern Minnesota to the eastern Great Lakes region today through Saturday. Expect light and variable winds through Saturday morning, becoming southeasterly and increasing into Saturday afternoon as high pressure exits and low pressure around 29.8 inches develops in the central High Plains. Conditions may become hazardous to small craft in southern Wisconsin nearshore regions during this time period.

Winds shift southerly and weaken as low pressure lifts into the northern Plains into Sunday. Low pressure then looks to deepen Monday into Monday night, bringing increasing southeasterly winds and building waves. Winds remain strong and southeasterly through Tuesday into Tuesday night, with isolated gales possible. Low pressure exits into southern Canada into Wednesday, with winds gradually shifting southwesterly and diminishing.

MH

Watches, warnings and advisories

WI: None. LM: None.