Marine Weather and Tide Forecast for Monona, WI

SHORT TERM
Issued 108 AM CDT Sat Jul 25 2026

Today through Monday Night:

Warm air and moisture advection will help drive an area of low clouds into the area into this morning, covering most of south central Wisconsin and perhaps into southeast Wisconsin as well. These low clouds should gradually scatter out during the afternoon, though if they hang on they will hold down high temperatures today. For now, will maintain highs in the middle 80s, with dew points climbing through the 60s bringing more humid conditions. Will need to watch the low clouds and see if they will mix out this afternoon.

There may be a period for small chances (around 20 percent) for an elevated thunderstorm to move southeast into areas north of Madison and Milwaukee this afternoon and tonight. This would be within the warm air advection and likely lifted from 850 mb or higher. If a storm were to develop, gusty winds and hail may occur with elevated tall skinny CAPE and increasing deep layer bulk shear.

However, the airmass over the area should be fairly well capped for mixed layer parcels, so anything that occurs would have to move southeast into the area. For now, will leave the 20 percent chances going in the far northern areas. Most of the area should remain dry.

South southwest winds are expected today. Any lake breeze in the afternoon is likely to remain near the shoreline, with south winds providing onshore flow near Port Washington and northward to Sheboygan.

There is a Moderate Swim Risk later this afternoon into early this evening for the Lake Michigan beaches in Sheboygan County.
Waves of 2 to 3 feet are expected from south winds. Breaking waves and currents are expected. Stay away from dangerous areas like piers, breakwalls, and river outlets.

There are better chances for thunderstorms at times mainly Sunday afternoon into Monday evening, as the area remains within northwest flow aloft and some warm air advection lingers in the low levels Sunday and Sunday night. A frontal boundary may develop and become quasi-stationary to the north of the area Sunday into Monday, which may help drive showers and storms there.

The low level jet nose may also try to point into southern Minnesota and west central Wisconsin later tonight into Sunday morning and try to develop showers and storms, which may try to shift southeast toward the area. There will still be a fairly decent cap in place over southern Wisconsin, though forecast soundings are trying to erode it more so than 24 hours ago.
Still, there is a lack of good upward vertical motion to focus convection over the area, so anything will probably have to shift southeast into the area Sunday into Sunday night.
Uncertainty remains fairly high at this time with timing and placement of possible storms.

If storms can move into the area, damaging winds and large hail are possible, given large mean layer CAPE over 3000 J/kg and increasing deep layer bulk shear values of 35 to 45 knots. Will message the severe potential as well as the uncertainty in timing and placement of storms.

Monday into Monday evening remains the best chances for severe storms to occur, as the forecast soundings are mixing out most of the cap in place with strong mean layer CAPE and deep layer bulk shear values remaining. There may be a 500 mb vorticity maximum that passes just northeast of the area later Monday into Monday evening, with a surface low possibly allowing for an MCS to develop in northern Wisconsin and shift south southeast through parts of the area. A lot of Monday into Monday evening severe chances will hinge on what happens Sunday into Sunday night, with any outflow or other boundaries that may move into the area. Uncertainty remains high, so will message this as well into Monday evening.

Hot and humid conditions are likely Sunday into Monday, with highs into the lower 90s, and dew points in the lower to middle 70s, allowing heat index values into the 97 to 104 degree range over most of the area. Thus, a Heat Advisory may eventually be needed for the area during this period.

Wood

LONG TERM
Issued 108 AM CDT Sat Jul 25 2026

Tuesday through Friday:

Northwest flow at 500 mb is generally expected to remain over the region through the rest of next week, with the ridge axis perhaps slowly shifting east and flattening out. It appears from ensembles that high pressure should build into the region for Tuesday into Wednesday, bringing warm and humid conditions but keeping dew points and heat index values lower than Sunday and Monday. More active weather may return to the area later this week, as low pressure and a cold front tries to shift southeast through the region. The warm and humid conditions should linger as well, per ensemble member trends and continued small NBM temperature spreads.

Wood

AVIATION
Issued 108 AM CDT Sat Jul 25 2026

An area of low ceilings in the 2000 to 3000 foot AGL range should move northeast into the area this morning, covering most of south central Wisconsin and perhaps into southeast Wisconsin as well. May see 1500 foot AGL ceilings at times toward Madison and Janesville terminals. These low clouds should gradually scatter out during the afternoon, though will need to watch and see if they will mix out this afternoon. If they do mix out, scattered to broken cumulus around 3500 to 4000 feet AGL are expected.

There may be a period for small chances (around 20 percent) for a thunderstorm to move southeast into areas north of Madison and Milwaukee this afternoon and tonight. If a storm were to develop, gusty winds and hail may occur. However, confidence is low at this time, and most of the area should remain dry. Storms may try to move southeast into the area later tonight into Sunday morning, but again confidence is low so will leave out of TAFs for now.

South southwest winds are expected today. Any lake breeze in the afternoon is likely to remain near the shoreline, with south winds providing onshore flow northward toward the Sheboygan terminal. The southeast lake breeze should remain east of the Milwaukee and Kenosha terminals. Light southwest winds are expected tonight.

Wood

MARINE
Issued 108 AM CDT Sat Jul 25 2026

Gusty south to southwest winds are expected across all of Lake Michigan into today, as low pressure around 29.5 inches shifts east across northern Ontario. Gusts up to 30 knots are expected over the far northern parts of the lake.

A frontal boundary will then stall mainly over Wisconsin and Lake Michigan tonight through most of Monday. This will result in increasing thunderstorm chances, with severe storms possible at times. Very warm and moist air flowing over the relatively cool waters may cause patchy dense fog Sunday into Monday. South to southwest winds will remain south of the boundary, with more variable winds to the north.

Northerly winds are expected Monday night through Wednesday, as high pressure around 30.0 inches builds over the Upper Great Lakes. Look for southerly winds and more unsettled weather to return later in the week.

Wood

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM...None.