Marine Weather and Tide Forecast for Sister Bay, WI
 | Sunrise 5:43 AM Sunset 8:12 PM Moonrise 11:01 PM Moonset 1:33 PM |
Marine Forecasts
NOTE: Zones updated 4/16/2026. Some zones changed. Use Edit if needed.
LMZ541 Rock Island Passage To Sturgeon Bay Wi- Sturgeon Bay To Two Rivers Wi-two Rivers To Sheboygan Wi- 1158 Am Cdt Wed Aug 5 2026
This afternoon - NE wind 5 to 10 kts veering E early in the afternoon. Waves 2 ft or less. A chance of showers and a slight chance of Thunderstorms.
Tonight - SE wind 5 to 10 kts backing n, then backing W after midnight. Waves 2 ft or less. Patchy fog after midnight.
Thursday - SW wind around 5 kts backing se in the late morning and afternoon. Waves 2 ft or less. Partly cloudy in the morning then clearing.
Thursday night - S wind 5 to 10 kts veering sw after midnight. Waves 2 ft or less. Mostly clear.
LMZ500
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No data
7 Day Forecast for Marine Location Near Sister Bay, WI
NEW! Add second zone forecast
FXUS63 KGRB 051739 AFDGRB
Area Forecast Discussion National Weather Service Green Bay WI 1239 PM CDT Wed Aug 5 2026
Forecast discussion for routine afternoon forecast issuance
KEY MESSAGES
- Scattered showers (20-30%) over east-central WI this afternoon as slow-moving cold front sinks south.
- Fog late tonight could be locally dense, especially across eastern WI.
- Rounds of showers and storms possible Friday through Monday, though confidence in storm timing and severity remains low.
- After today, near normal high temperatures in the low to mid 80s through most of next week.
DISCUSSION
Issued at 1239 PM CDT Wed Aug 5 2026
Near term through Thursday...Main concern are chances for scattered showers this afternoon. Already added 20-30% chances for scattered showers this afternoon especially over east- central WI. Peak timing will be from 2p-5p. Forcing will be provided by shortwave over northern Iowa and weak 850-600mb frontogenesis enhanced by right entrance of upper jet. Thunder potential low even as shower coverage will be maximized during peak heating as MUCAPE will be well under 500 J/kg being held in check by current cloud cover. Limited sunshine will lead to highs this afternoon staying in the 70s for most areas.
Risk for scattered showers ends early this evening. Once clouds clear out, temps cooling into the upper 50s and light winds could lead to areas of fog especially northeast and east-central WI. MOS guidance suggests that the fog could become locally dense. After the fog diminishes early Thursday morning, expect skies to be mostly sunny as high pressure will be overhead. Will see scattered fair wx cu through the afternoon. Highs will be warmer than today, with many locations reaching the lower 80s.
Shower and thunderstorm chances beginning Friday...Weak front drops across WI Friday afternoon through late Friday night, interacting with ribbon of higher instability (MLCAPEs 1000+ J/kg) will allow showers and scattered storms to blossom over northern WI. Strongest shortwave and large scale lift stays north of Lake Superior late Friday, so expect greatest coverage of showers to stay over northern WI into Upper Michigan through Friday evening. This is also where smaller chances of any severe storms will be near shear over 30 kts. Smaller chances of showers and storms will spread over the rest of the area Friday evening as the front shifts east/southeast.
For the weekend and into early next week, western Great Lakes region remains on edge of western ridge/heat dome. Thus we will stay on the gradient of steeper mid-level lapse rates over the central Plains. Better chances of more organized convection will remain south and west, but seasonably stronger northwest flow and any shortwaves within the flow could kick off at least a couple rounds of showers and storms this weekend through Monday. Overall though given lack of stronger shortwaves and/or abundant instability pops remain pretty low throughout. Based on LREF which is blend of ensembles, best signal for rain (probabilities of 0.05 inch or more) would be late Saturday night, then again Sunday night through Monday.
In terms of severe and heavy rain potential, machine learning guidance has increased signal for possible severe nearby both Saturday and Sunday. Greater risks are still southwest of Wisconsin though. ECMWF EFI points to Sunday as the greater risk day, but even then the stronger signal remains over northern IL and southern WI. Will continue to monitor for any severe weather potential.
Similar pattern to the risk for heavy rain, with parts of central WI placed in a marginal risk (1 of 5) for Saturday/Saturday night and Sunday/Sunday night. Frontal boundary over the area early next week gradually will sag south leading to lower chances for rain by Tuesday/Wednesday.
Temperatures/smoke...Temperatures will be near normal into next week with highs in the lower to middle 80s. Humidity levels will be comfortable, with dewpoints reading mainly in the upper 50s to low 60s. Elevated smoke layer departs by this evening. Another push of elevated smoke returns on Friday ahead of the approaching front. No significant impacts to visibility or air quality are expected.
AVIATION
for 18Z TAF Issuance Issued at 1239 PM CDT Wed Aug 5 2026
A few showers may impact eastern WI TAF sites through 22z. Even with the showers, conditions should remain VFR. Very small potential of thunder with the showers given minimal instability and weak forcing.
Late tonight, good signal for fog developing over eastern WI.
Visibility less than 1SM in play at GRB/ATW/MTW, with 1-3SM vsby possible at AUW/CWA. Low-levels drying out enough at RHI today to prohibit a repeat of the fog seen there this morning. Fog will dissipate by 14z-15z on Thursday. Rest of day will feature FEW-SCT VFR cu, especially over eastern WI.
GRB WATCHES/WARNINGS/ADVISORIES
None.
Area Forecast Discussion National Weather Service Green Bay WI 1239 PM CDT Wed Aug 5 2026
Forecast discussion for routine afternoon forecast issuance
KEY MESSAGES
- Scattered showers (20-30%) over east-central WI this afternoon as slow-moving cold front sinks south.
- Fog late tonight could be locally dense, especially across eastern WI.
- Rounds of showers and storms possible Friday through Monday, though confidence in storm timing and severity remains low.
- After today, near normal high temperatures in the low to mid 80s through most of next week.
DISCUSSION
Issued at 1239 PM CDT Wed Aug 5 2026
Near term through Thursday...Main concern are chances for scattered showers this afternoon. Already added 20-30% chances for scattered showers this afternoon especially over east- central WI. Peak timing will be from 2p-5p. Forcing will be provided by shortwave over northern Iowa and weak 850-600mb frontogenesis enhanced by right entrance of upper jet. Thunder potential low even as shower coverage will be maximized during peak heating as MUCAPE will be well under 500 J/kg being held in check by current cloud cover. Limited sunshine will lead to highs this afternoon staying in the 70s for most areas.
Risk for scattered showers ends early this evening. Once clouds clear out, temps cooling into the upper 50s and light winds could lead to areas of fog especially northeast and east-central WI. MOS guidance suggests that the fog could become locally dense. After the fog diminishes early Thursday morning, expect skies to be mostly sunny as high pressure will be overhead. Will see scattered fair wx cu through the afternoon. Highs will be warmer than today, with many locations reaching the lower 80s.
Shower and thunderstorm chances beginning Friday...Weak front drops across WI Friday afternoon through late Friday night, interacting with ribbon of higher instability (MLCAPEs 1000+ J/kg) will allow showers and scattered storms to blossom over northern WI. Strongest shortwave and large scale lift stays north of Lake Superior late Friday, so expect greatest coverage of showers to stay over northern WI into Upper Michigan through Friday evening. This is also where smaller chances of any severe storms will be near shear over 30 kts. Smaller chances of showers and storms will spread over the rest of the area Friday evening as the front shifts east/southeast.
For the weekend and into early next week, western Great Lakes region remains on edge of western ridge/heat dome. Thus we will stay on the gradient of steeper mid-level lapse rates over the central Plains. Better chances of more organized convection will remain south and west, but seasonably stronger northwest flow and any shortwaves within the flow could kick off at least a couple rounds of showers and storms this weekend through Monday. Overall though given lack of stronger shortwaves and/or abundant instability pops remain pretty low throughout. Based on LREF which is blend of ensembles, best signal for rain (probabilities of 0.05 inch or more) would be late Saturday night, then again Sunday night through Monday.
In terms of severe and heavy rain potential, machine learning guidance has increased signal for possible severe nearby both Saturday and Sunday. Greater risks are still southwest of Wisconsin though. ECMWF EFI points to Sunday as the greater risk day, but even then the stronger signal remains over northern IL and southern WI. Will continue to monitor for any severe weather potential.
Similar pattern to the risk for heavy rain, with parts of central WI placed in a marginal risk (1 of 5) for Saturday/Saturday night and Sunday/Sunday night. Frontal boundary over the area early next week gradually will sag south leading to lower chances for rain by Tuesday/Wednesday.
Temperatures/smoke...Temperatures will be near normal into next week with highs in the lower to middle 80s. Humidity levels will be comfortable, with dewpoints reading mainly in the upper 50s to low 60s. Elevated smoke layer departs by this evening. Another push of elevated smoke returns on Friday ahead of the approaching front. No significant impacts to visibility or air quality are expected.
AVIATION
for 18Z TAF Issuance Issued at 1239 PM CDT Wed Aug 5 2026
A few showers may impact eastern WI TAF sites through 22z. Even with the showers, conditions should remain VFR. Very small potential of thunder with the showers given minimal instability and weak forcing.
Late tonight, good signal for fog developing over eastern WI.
Visibility less than 1SM in play at GRB/ATW/MTW, with 1-3SM vsby possible at AUW/CWA. Low-levels drying out enough at RHI today to prohibit a repeat of the fog seen there this morning. Fog will dissipate by 14z-15z on Thursday. Rest of day will feature FEW-SCT VFR cu, especially over eastern WI.
GRB WATCHES/WARNINGS/ADVISORIES
None.
| Stations | Dist | Age | Wind | Air | Water | Waves | inHg | DewPt |
| NPDW3 - Northport Pier at Death's Door WI | 10 mi | 118 min | NNW 8G | 30.06 | ||||
| 45002 - N MICHIGAN- Halfway between North Manitou and Washington Islands. | 39 mi | 38 min | N 9.7G | 66°F | 67°F | 1 ft | 30.01 |
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