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SuperiorWaves

Aug 1, 2026 at 3:03 PM

Thunder Bay, Ontario · right here

Read this before your first Superior run

Superior is not a big inland lake. It is a small ocean that happens to be fresh.

Three things catch people out, every single season:

The water is cold enough to kill you in August. Air at 26 C means nothing when the water is at 9 C. Cold shock takes your breath in seconds and your hands in ten minutes.
Fetch, not wind speed, decides what the water does. Fifteen knots behind the Sibley Peninsula is glass. The same fifteen knots at Marquette with 200 km of open lake upwind is a different lake entirely. That is exactly what the forecast on this site models.
An offshore wind lies to you. The beach looks calm because the chop has not had room to build yet. Every kilometre out is a kilometre you have to fight back.

Wear the PFD. Tell somebody your plan. Pick a bail-out shore before you launch.

Sea-Doo

Conditions at Thunder Bay, Ontario today

Today

Sep 1 · light 7:15 AM to 8:38 PM

Good · 77

Good: best 9 AM to 2 PM, waves around 0.3 m (1 ft).

0.2-0.4 m (0.7-1.5 ft)

gusts 22 kt

16 to 27 C

best 9 AM - 2 PM

Hour by hour

12 am

0.3m

3kt ESE 18°C

1 am

0.3m

2kt E 18°C

2 am

0.3m

2kt ESE 18°C

3 am

0.3m

2kt SE 18°C

4 am

0.3m

1kt SSW 17°C

5 am

0.2m

2kt NNE 17°C

6 am

0.2m

2kt ENE 17°C

7 am

0.2m

1kt NNE 16°C

8 am

0.2m

0kt W 16°C

9 am

0.2m

1kt NNW 17°C

10 am

0.2m

2kt WNW 19°C

11 am

0.3m

4kt W 22°C

12 pm

0.3m

8kt WSW 24°C

1 pm

0.3m

11kt WSW 25°C

2 pm

0.3m

13kt WSW 26°C

3 pm

0.4m

14kt W 27°C

4 pm

0.4m

14kt W 27°C

5 pm

0.4m

13kt W 25°C

6 pm

0.4m

12kt W 25°C

7 pm

0.4m

11kt W 24°C

8 pm

0.4m

9kt W 23°C

9 pm

0.4m

8kt WNW 21°C

10 pm

0.4m

7kt WNW 20°C

11 pm

0.3m

6kt WNW 18°C

Tuesday 9:00 AM

Daylight

Excellent · 94

Waves

0.2 m

0.8 ft · sets to 1.2 ft

Wind

1 kt

from the NNW · gusts 1 kt

Fetch

0 km

Very short. Little room for waves to build.

Wave period

3.9 s

Longer, rolling water

Air

17 C

feels like 19 C

Water

14 C

Genuinely cold. Under an hour of use.

Visibility

12.2 km

Clear

Storm energy

0

Stable air

Why this hour scores 94

Windows through the day

Light ripple at 0.2 m (0.8 ft), just enough to know you are on water rather than a mirror. It will feel chilly out there, around 14 C on the ski even though the shore reads 27 C. Splash top and a warm layer under it. You will cool off fast the moment you stop moving. Water at 14 C. Fine for a quick dip if you are brave, not somewhere to linger. Aim for 9 AM to 2 PM. It goes downhill after that, so do not be the last one off the water.

The full picture

For sea-doo / personal watercraft today, this is a good day, scoring 77 out of 100 across daylight hours. Waves range from 0.2 m (0.7 ft) to 0.4 m (1.5 ft), with wind from the W gusting to 22 knots at its worst. Daylight runs 7:15 AM to 8:38 PM. The best window is 9:00 AM to 2:00 PM (5 hours), and the single best hour is around 9 AM. In that window the water runs to about 0.3 m (1 ft) with wind to 11 knots. After 2:00 PM the best you will get is good, with the water running toward 0.3 m (1.1 ft), so plan to be back on the trailer by then. Earlier in the day it only reaches poor, so there is no advantage to launching at first light. Conditions flip back and forth through the day rather than settling, so treat any window as provisional and keep checking. What is working against you, at the worst of it: Visibility down to 0.3 km. Superior fog forms fast over cold water and it will hide the shoreline and other traffic. Do not go out without a chart plotter. Worth watching: The shore says 16 C, but moving across the water it will feel more like 14 C. Nice enough in the sun, nippy the moment you stop. Splash top and a warm layer under it. You will cool off fast the moment you stop moving. Water is 14 C. Survivable but genuinely cold. Assume you have well under an hour of useful movement if you end up in it. In your favour, at the best of it: 17 C on shore, feeling like 14 C on the ski. Splash top and a warm layer under it. You will cool off fast the moment you stop moving. Light chop at 0.2 m (0.8 ft), biggest sets around 0.4 m (1.2 ft). Comfortable. Light at 1 knots from the NNW. Nothing to fight.

What drove this call

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