Marine forecast
Northerly Island to Calumet Harbor, IL
- current wind
- 9 kt W
- Gusts
- 13 kt
- Seas
- 0.7 ft
- Air
- 78°F
- 72-hr peak
- 24 kt
Observed Tue 2:15 PM | LMZ742
- Gusts now
- 13 kt
- Seas now
- 0.7 ft
- Air
- 78°F
- 72-hr peak
- 24 kt
- Peak seas
- 4 ft
In brief
At 2:15 pm CDT on Oct 13, 2026, NDBC station CNII2 (Northerly Isle, IL, 4 miles away) measured wind from the W at 9 kt, gusting to 13 kt; buoy 45198 measured seas of 0.7 ft. The NWS forecast for Northerly Island to Calumet Harbor, IL issued at 9:41 am CDT on Oct 13, 2026 reads, for rest of today: “West winds 10 to 20 kt becoming northeast and diminishing to around 10 kt in the afternoon. Partly cloudy.”
Source: National Weather Service Chicago/Romeoville IL forecast; NDBC observations
Wind forecast · ktPeak 24 kt
Seas forecast · ftPeak 4 ft
NWS marine forecast
| Period | Forecast |
|---|---|
| Rest Of Today | West winds 10 to 20 kt becoming northeast and diminishing to around 10 kt in the afternoon. Partly cloudy. Waves 1 to 2 ft. |
| Tonight | Northeast winds around 5 kt. Showers and thunderstorms likely. Waves 1 to 3 ft. |
| Wednesday | Northeast winds 10 to 20 kt. Chance of showers in the morning. Waves 2 to 4 ft building to 3 to 5 ft occasionally to 8 ft late in the afternoon. |
| Wednesday Night | Northeast winds 15 to 20 kt becoming east overnight. Slight chance of rain overnight. Waves 4 to 6 ft occasionally to 8 ft. A small craft advisory will likely be needed. |
Issued Tue 9:41 AM by Chicago/Romeoville IL (product NSHLOT).
Recent buoy conditions
| Time | Wind | Gust | Seas | Water |
|---|---|---|---|---|
| Tue 2:15 PM | 9 kt W | 13 kt | — | — |
| Tue 1:45 PM | 8 kt WSW | 12 kt | — | — |
| Tue 12:45 PM | 7 kt WSW | 10 kt | — | — |
| Tue 11:45 AM | 7 kt WSW | 13 kt | — | — |
| Tue 10:45 AM | 5 kt WSW | 14 kt | — | — |
| Tue 9:45 AM | 7 kt WSW | 14 kt | — | — |
| Tue 8:45 AM | 11 kt W | — | — | — |
| Tue 7:45 AM | 8 kt WSW | 9 kt | — | — |
| Tue 6:45 AM | 6 kt WSW | 7 kt | — | — |
| Tue 5:45 AM | 6 kt WSW | 7 kt | — | — |
| Tue 4:45 AM | 6 kt SSW | 8 kt | — | — |
| Tue 3:45 AM | 3 kt W | 9 kt | — | — |
Observed Tue 2:15 PM at NDBC buoy CNII2 (Northerly Isle, IL), 4.2 miles away. Seas from buoy 45198 (Chicago Buoy), 6.0 miles away, at Tue 2:10 PM.
Frequently asked questions
What is the marine forecast for Northerly Island to Calumet Harbor today?
Rest Of Today: West winds 10 to 20 kt becoming northeast and diminishing to around 10 kt in the afternoon. Partly cloudy. Waves 1 to 2 ft.
Is there a small craft advisory for Northerly Island to Calumet Harbor?
No advisories, warnings or watches are in effect for NWS zone LMZ742 as of the last update on this page. Advisories can be issued at any time; check the current bulletin before leaving the dock.
How high are the waves at Northerly Island to Calumet Harbor right now?
Seas are running 0.7 ft, measured at NDBC buoy CNII2 Tue 2:15 PM, 4.2 miles from this zone. The forecast peaks at 4.0 ft Wed 8 PM.
What do the wind speeds in knots mean?
One knot is 1.15 mph. The National Weather Service issues a small craft advisory for sustained winds of roughly 22–33 knots or hazardous seas, a gale warning at 34–47 knots, and a storm warning at 48 knots and above. Exact advisory thresholds vary by forecast office and by water body — a bay reaches dangerous chop at a lower wind speed than open ocean.
Where does this forecast come from?
The forecast text is the National Weather Service's own marine bulletin for zone LMZ742, issued by Chicago/Romeoville IL, reproduced in full. The wind and seas charts are drawn from the NWS gridded forecast for a point inside the zone. Observations come from the nearest reporting NDBC buoy. We are not affiliated with NOAA or the National Weather Service.
Forecast: NOAA/NWS product NSHLOT, issued Tue 9:41 AM. Observations: NOAA National Data Buoy Center station CNII2, read Tue 2:15 PM. Retrieved Oct 13, 2:42 PM. Conditions offshore change faster than any page can be rebuilt, so check the current NWS bulletin and your own instruments before going out.