North Flathead Lake

The north end, the area from Somers/Bigfork as far south as Cedar Island and the Painted Rocks, can have as many as three breezes throughout a typical summer day.

The morning thermal (the "northerly" as the local sailors call it) drops down from the mountains in the north end of the valley onto the lake starting just after sunrise (6 am or so in July). The northerly usually lasts until noon or 1 pm, and is generally strongest between 8 and 10 am. There is moderate fetch from the north shore to Lakeside, so waves are generally one foot to two feet, and the average strength of the breeze is usually between six and eight knots. This is a very pleasant time to be out sailing, as there are generally few, if any, other boats on the water and the sun is rising over the mountains on the east side of the lake. A sign that the northerly is dying is when it begins to veer (shift to the east, or clockwise).

Generally, but not always, the "southerly" will come in from the south, bending around Angel Point and sailors will be able to see the darker water approaching well before the actual breeze arrives. The southerly will usually come in between 1 and 2 pm and last well into the afternoon or early evening, sometimes as late as 7 or 7:30 pm. The fetch from the south is quite long, and the water is deeper out in the lake, causing swells of two to three feet, sometimes larger.

After the southerly dies down as the north valley begins to cool, the evening thermal will kick in. As the sun sets beyond Blacktail Mountain, the air begins to cool and fall out of the valleys. Somers Bay generally gets a nice seven to eight knot breeze, tending to be stronger in the early summer when the temperature differential from the air to the water is greater. Lakeside Bay generally gets about a knot or so less most evenings, but the breeze comes right off the shore and therefore there are only small wavelets or ripples caused by the breeze and the sailing is often fantastic. As the boat moves through the water it makes little or no sound, and the experience is quite pleasant.