Marine Weather and Tide Forecast for Winthrop Harbor, IL

DISCUSSION
Issued at 1252 PM CST Fri Nov 6 2026

The coldest airmass so far this season over the area has led to temps struggling to rise out of the mid 40s early this afternoon, with 50 degrees looking to be out of reach for a vast majority of the area. With a surface ridge drifting toward the area from the west, limited non-diurnal cloud cover upstream, and cool daytime temps, we are well on our way to the coldest night and first hard freeze for many this fall. Do have some concern that shallow stratus attempts to expand inland off Lake Michigan this evening, but lowering inversion heights through the night should erode any potential lingering stratus overnight. Overall, temps tonight are expected to fall into the mid to upper 20s away from the core of the Chicago metro and northwest Indiana downwind of Lake Michigan. In colder areas tonight, shallow fog may develop in lieu of heavy frost.
Otherwise, isolated lake effect rain showers will persist into mainly northern Porter County through early evening before exiting to the east.

A series of weak mid-level troughs and ridges within broader WNW flow aloft will cross the northern Great Lakes through early next week, leading to precip-free conditions and daytime highs gradually moderating back to the low to mid 60s Monday and Tuesday.

Consensus ensemble guidance suggests that an increasingly amplified mid-level pattern with hints at a developing omega block will develop across much of North America late next week/weekend. The eastern trough of this pattern does show signs of settling over the Great Lakes region during this period.
With the main ridge situated in a SSW to NNE orientation into Hudson Bay, seasonably cool temps and north to northeast low- level flow will support periods of lake effect rain showers aimed into both northwest Indiana and northeast Illinois. Cannot fully rule out our first snow flakes of the season given some ensemble members supporting a more westward presentation of the trough and corresponding colder airmass. Will need to keep a close eye on any trends toward colder solutions as early as Thursday morning but especially into Friday.

Kluber

AVIATION /06Z TAFS THROUGH 12Z SUNDAY/
Issued at 1120 PM CST Fri Nov 6 2026

The only forecast concern through the period is the potential for patchy fog early Saturday morning and again early Sunday morning. Confidence is low for fog overnight into early Saturday morning with low level winds likely remaining strong enough to keep the low levels mixed enough. Any fog that does form will likely be shallow/patchy and will continue with no mention in this forecast. By early Sunday morning, low level winds will also likely be too strong to allow anything more than patchy/ shallow fog. The low level winds Sunday morning may be strong enough that trends will need to be monitored for low level wind shear.

Surface winds will be light west/northwest overnight into Saturday morning, with some areas becoming light and variable or calm. Winds will slowly turn more westerly up to 10kts Saturday and then turn to the southwest Saturday evening. cms

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...Small Craft Advisory until midnight CST tonight for the IL nearshore waters.

Small Craft Advisory until 9 AM CST Saturday for Calumet Harbor IL to Burns Harbor IN.

Small Craft Advisory until 3 PM CST Saturday for Burns Harbor to Michigan City IN.