Marine Weather and Tide Forecast for Williams Bay, WI
April 21, 2025 5:54 AM CDT (10:54 UTC) Change Location
![]() | Sunrise 6:01 AM Sunset 7:43 PM Moonrise 3:01 AM Moonset 12:21 PM |
LMZ646 Wind Point Wi To Winthrop Harbor Il- 505 Am Cdt Mon Apr 21 2025
.gale warning in effect through this evening - .
Today - Southwest wind 15 to 25 knots veering west late in the afternoon. Gusts up to 35 knots. Slight chance of showers in the morning. Waves 5 to 7 feet subsiding to 3 to 4 feet.
Tonight - West wind 15 to 20 knots with gusts to around 25 knots easing to 10 to 15 knots in the late evening and early morning, then easing to 5 to 10 knots early in the morning. Partly cloudy through around midnight then becoming clear. Waves around 1 foot.
Tuesday - Southwest wind 5 to 10 knots backing southeast late in the morning, then rising to 10 to 15 knots early in the afternoon backing east late in the afternoon. Chance of showers through the day. Waves around 1 foot.
Tuesday night - East wind 10 to 15 knots veering southeast late in the evening, then becoming southwest 5 to 10 knots after midnight veering west early in the morning. Rain showers likely and a chance of Thunderstorms. Waves 1 to 2 feet.
LMZ600
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7 Day Forecast for Marine Location Near Williams Bay, WI

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Area Discussion for Milwaukee/Sullivan, WI
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FXUS63 KMKX 210849 AFDMKX
Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 349 AM CDT Mon Apr 21 2025
KEY MESSAGES
- Some lingering showers this morning, but otherwise today will be gusty through the afternoon with gusts up to around 25-35 mph possible.
- Thunderstorm chances return Tuesday morning/afternoon with a potential for an isolated strong to severe thunderstorm or two capable of producing hail. May be an additional window for thunderstorms Tuesday evening in southwest WI, but more uncertainty with this round.
- Temps will warm up through the end of the week with well above normal highs and there will be additional rain and thunderstorm chances for the second half of the week.
SHORT TERM
Issued 339 AM CDT Mon Apr 21 2025
Today through Tuesday night:
The surface low and accompanying mid-level shortwave trough continue to lift across central WI and into northern portions of Lake Michigan through the morning. The bulk of the shower activity has already pushed through overnight and a dry slot is limiting additional widespread coverage from developing.
However, sporadic/scattered light shower chances will linger through daybreak before diminishing by mid morning hours as a cold front pushes through the area. Looking at drier conditions behind the cold front for the rest of day, but given the low deepening to sub 1000mb, the pressure gradient will remain tight across southern WI. Thus resulting in stronger westerly gusts of 20-30 mph through the afternoon with the strongest gusts possibly even approaching 35-40 mph for east-central portions of WI.
Otherwise, winds will diminish through the evening as high pressure and upper-level ridge quickly traverses just south of the area. Should see light winds and cool conditions overnight with lows dipping into the mid to upper 30s.
Then a mid-level shortwave trough from the northern Plains is progged to follow right behind the ridge and push into the Upper Midwest later tonight/early Tuesday morning. This system will the focus for our next round or two of showers/storms. The associated surface low paired with the upper-level wave is expected to break away and meander up the ND/MN border through Tuesday. Ahead of it a wing of low-level WAA will lift up the Upper Mississippi River Valley Tuesday morning. The low-level dynamics paired with a swath of MUCAPE 500-750 J/kg, steep mid- level lapse rates (7.5-8.0C/km), nose of 850mb LLJ, and increased deep layer shear looks to support elevated convection.
With the morning round of elevated storms, could see a few stronger and even an isolated severe storm or two capable of producing large hail develop across southern WI daybreak through the early afternoon.
There may be additional round of showers and convection to develop later in the afternoon and early evening if the surface warm front and nose of the higher surface moisture lifts north of the WI/IL border. There is a bit more uncertainty with this round as the environment may not have enough time to recover after the morning round of storms along with easterly flow off of the lake preventing it from lifting. However there are hints that it may have enough momentum to lift north into our CWA especially for south-central and southwestern portions. If the warm front is able to make it north of the Cheddar Curtain, then could see more surface based convection develop, which may be capable of producing hail and gusty winds. Again, uncertainty remains greater as it looks to be narrow window that favors convection development into the evening hours.
Wagner
LONG TERM
Issued 339 AM CDT Mon Apr 21 2025
Wednesday through Sunday:
Wednesday morning is expected to remain dry at this time as another surface warm front sharpens just south of the border through the daytime hours. By Wednesday evening, thunderstorm activity is expected to blossom and eventually move into southwestern WI Wednesday night into Thursday following warm advection of the LLJ northward. By Thursday morning, most of the shower activity with the front should be north of our CWA, and we stand to remain dry most of the day given most of the better forcing for ascent will be either north or west of us. Thursday night, however, a slow moving frontal boundary is expected to move toward western WI bringing chances for overnight showers and storms into Friday morning. Models depict the boundary lingering enough on Friday to allow some destabilization and some more shower and storm formation Friday afternoon over southeast Wisconsin before the front clears the state.
Beyond, high pressure looks to take hold following the frontal passage with seasonable temperatures in the upper 50s to low 60s remaining over the region.
CMiller
AVIATION
Issued 339 AM CDT Mon Apr 21 2025
Widespread MVFR and pockets of IFR ceilings sit over southern WI this morning associated with the surface low. Expecting the low to lift northeast through the day, but lower ceiling are progged to linger through the remainder of the morning and into the afternoon before clearing by this evening. Additionally will see breezy southerly winds turn westerly and increase through the morning as well. Looking at gusts of 25-30kt this afternoon.
Conditions improve and winds ease by the evening as high pressure quickly pushes through the area overnight. Then another system treks into the area from the northern Plains and will bring another period of lower flight conditions along with increased shower and thunderstorms chances Tuesday morning.
Wagner
MARINE
Issued 339 AM CDT Mon Apr 21 2025
Low pressure will continue north-northeast and track across northern Lake Michigan through today and moving to north of Lake Huron tonight. Breezy southeasterly winds will quickly become southerly, then southwesterly after daybreak, with patchy gale force gusts over most of the open waters through today. A Gale Warning remains in effect from 7AM to 7PM CDT for areas south of the center of the low pressure.
Winds then become westerly late this afternoon and evening and will gradually ease overnight into Tuesday morning. Light northwesterly will begin to turn through Tuesday afternoon as the surface high pressure passes pushes east of the Lake. Winds then increase and become southeasterly Tuesday afternoon/evening ahead of a warm front lifts and stalls across the southern third of Lake Michigan Tuesday evening. Lighter winds are expected for the middle of the week as high pressure builds in from the west.
CMiller/Wagner
MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Small Craft Advisory
LMZ643-LMZ644-LMZ645-LMZ646 until 7 AM Monday.
Gale Warning...LMZ080-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646- LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870- LMZ872-LMZ874-LMZ876-LMZ878...7 AM Monday to 7 PM Monday.
Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 349 AM CDT Mon Apr 21 2025
KEY MESSAGES
- Some lingering showers this morning, but otherwise today will be gusty through the afternoon with gusts up to around 25-35 mph possible.
- Thunderstorm chances return Tuesday morning/afternoon with a potential for an isolated strong to severe thunderstorm or two capable of producing hail. May be an additional window for thunderstorms Tuesday evening in southwest WI, but more uncertainty with this round.
- Temps will warm up through the end of the week with well above normal highs and there will be additional rain and thunderstorm chances for the second half of the week.
SHORT TERM
Issued 339 AM CDT Mon Apr 21 2025
Today through Tuesday night:
The surface low and accompanying mid-level shortwave trough continue to lift across central WI and into northern portions of Lake Michigan through the morning. The bulk of the shower activity has already pushed through overnight and a dry slot is limiting additional widespread coverage from developing.
However, sporadic/scattered light shower chances will linger through daybreak before diminishing by mid morning hours as a cold front pushes through the area. Looking at drier conditions behind the cold front for the rest of day, but given the low deepening to sub 1000mb, the pressure gradient will remain tight across southern WI. Thus resulting in stronger westerly gusts of 20-30 mph through the afternoon with the strongest gusts possibly even approaching 35-40 mph for east-central portions of WI.
Otherwise, winds will diminish through the evening as high pressure and upper-level ridge quickly traverses just south of the area. Should see light winds and cool conditions overnight with lows dipping into the mid to upper 30s.
Then a mid-level shortwave trough from the northern Plains is progged to follow right behind the ridge and push into the Upper Midwest later tonight/early Tuesday morning. This system will the focus for our next round or two of showers/storms. The associated surface low paired with the upper-level wave is expected to break away and meander up the ND/MN border through Tuesday. Ahead of it a wing of low-level WAA will lift up the Upper Mississippi River Valley Tuesday morning. The low-level dynamics paired with a swath of MUCAPE 500-750 J/kg, steep mid- level lapse rates (7.5-8.0C/km), nose of 850mb LLJ, and increased deep layer shear looks to support elevated convection.
With the morning round of elevated storms, could see a few stronger and even an isolated severe storm or two capable of producing large hail develop across southern WI daybreak through the early afternoon.
There may be additional round of showers and convection to develop later in the afternoon and early evening if the surface warm front and nose of the higher surface moisture lifts north of the WI/IL border. There is a bit more uncertainty with this round as the environment may not have enough time to recover after the morning round of storms along with easterly flow off of the lake preventing it from lifting. However there are hints that it may have enough momentum to lift north into our CWA especially for south-central and southwestern portions. If the warm front is able to make it north of the Cheddar Curtain, then could see more surface based convection develop, which may be capable of producing hail and gusty winds. Again, uncertainty remains greater as it looks to be narrow window that favors convection development into the evening hours.
Wagner
LONG TERM
Issued 339 AM CDT Mon Apr 21 2025
Wednesday through Sunday:
Wednesday morning is expected to remain dry at this time as another surface warm front sharpens just south of the border through the daytime hours. By Wednesday evening, thunderstorm activity is expected to blossom and eventually move into southwestern WI Wednesday night into Thursday following warm advection of the LLJ northward. By Thursday morning, most of the shower activity with the front should be north of our CWA, and we stand to remain dry most of the day given most of the better forcing for ascent will be either north or west of us. Thursday night, however, a slow moving frontal boundary is expected to move toward western WI bringing chances for overnight showers and storms into Friday morning. Models depict the boundary lingering enough on Friday to allow some destabilization and some more shower and storm formation Friday afternoon over southeast Wisconsin before the front clears the state.
Beyond, high pressure looks to take hold following the frontal passage with seasonable temperatures in the upper 50s to low 60s remaining over the region.
CMiller
AVIATION
Issued 339 AM CDT Mon Apr 21 2025
Widespread MVFR and pockets of IFR ceilings sit over southern WI this morning associated with the surface low. Expecting the low to lift northeast through the day, but lower ceiling are progged to linger through the remainder of the morning and into the afternoon before clearing by this evening. Additionally will see breezy southerly winds turn westerly and increase through the morning as well. Looking at gusts of 25-30kt this afternoon.
Conditions improve and winds ease by the evening as high pressure quickly pushes through the area overnight. Then another system treks into the area from the northern Plains and will bring another period of lower flight conditions along with increased shower and thunderstorms chances Tuesday morning.
Wagner
MARINE
Issued 339 AM CDT Mon Apr 21 2025
Low pressure will continue north-northeast and track across northern Lake Michigan through today and moving to north of Lake Huron tonight. Breezy southeasterly winds will quickly become southerly, then southwesterly after daybreak, with patchy gale force gusts over most of the open waters through today. A Gale Warning remains in effect from 7AM to 7PM CDT for areas south of the center of the low pressure.
Winds then become westerly late this afternoon and evening and will gradually ease overnight into Tuesday morning. Light northwesterly will begin to turn through Tuesday afternoon as the surface high pressure passes pushes east of the Lake. Winds then increase and become southeasterly Tuesday afternoon/evening ahead of a warm front lifts and stalls across the southern third of Lake Michigan Tuesday evening. Lighter winds are expected for the middle of the week as high pressure builds in from the west.
CMiller/Wagner
MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Small Craft Advisory
LMZ643-LMZ644-LMZ645-LMZ646 until 7 AM Monday.
Gale Warning...LMZ080-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646- LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870- LMZ872-LMZ874-LMZ876-LMZ878...7 AM Monday to 7 PM Monday.
Stations | Dist | Age | Wind | Air | Water | Waves | inHg | DewPt |
WHRI2 - Waukegan Harbor, IL | 39 mi | 114 min | S 5.1G | 51°F | ||||
MLWW3 - Milwaukee, WI | 45 mi | 44 min | S 7G | 52°F | ||||
45199 | 46 mi | 84 min | S 14 | 41°F | 39°F | 5 ft | 29.60 |
Wind History for Calumet Harbor, IL
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