FAQ: Flathead Lake Water Temperature and Conditions
Starting in late spring, Flathead Lake becomes one of the best sailing destinations in the Rocky Mountains. The glacier-fed water, gentle breezes, and mountain views are excellent for long days learning a new skill or picking back up where you left off last sailing season.
Before you head out onto Flathead Lake, it helps to know what to expect. These are some frequently asked questions our ASA sailing instructors get from visitors when they sail with Go Sail Flathead Lake.
What’s the weather like at Flathead Lake in August?
The weather at Flathead Lake varies throughout the year. While it starts to warm up in the spring, the sailing season lasts from May to September, with August being our favorite time at Go Sail Flathead Lake. The temperatures are mild, the wind is typically around 10 to 15 knots, and there’s usually less rain than earlier in the summer. Sailors can expect highs around 80°F on many August days, but lows can still drop into the high 40s. Keep in mind the temperature on the water is usually chiller than on shore so pack a light jacket!
What is the water temperature at Flathead Lake in the summer?
Summers are relatively warm in Montana, especially after June. The water temperature begins to warm up midsummer, too, with surface temperatures approaching 70°F by August. If you sail with us in May or June, the water hasn’t had a chance to warm up as much yet. During this time, the water temperature is usually between 50°F and 63°F.
Is Flathead Lake warm enough to swim?
Yes, Flathead Lake is warm enough to swim in during the sailing season. With warmer temperatures in July and August, visitors often enjoy swimming at the beaches and in the bays around one of Montana’s favorite summertime destinations.
How cold is Flathead Lake in September?
Flathead Lake gets cold in the winter, but fall can be surprisingly temperate. While temperatures do begin cooling off in October, September has plenty of sunny days in the 60s. Nighttime can be chillier, so you may want to add some warmer clothes to your packing list.
Does Flathead Lake get windy in the afternoon?
Flathead Lake sailing conditions are usually excellent, with winds typically not exceeding 15 knots on many days. But there are afternoons when winds can pick up and bring higher gusts, which can cause surprisingly rough waves out on the open water. At Go Sail Flathead Lake, we do our best to monitor conditions and warn visitors when it’s not safe to sail. It’s especially important to check the forecast when kayaking to avoid unsafe swells that can be over 3 feet.
What is the best time of day to sail on Flathead Lake?
Sailing on Flathead Lake can be enjoyable at different times of the day, depending on what you plan to do. The mornings offer calm sailing and wildlife viewing opportunities, while evenings are nice for a sunset sail. Winds can pick up as the day goes on, so always check the forecast or ask an ASA sailing instructor if you have concerns.
Does warmer water on Flathead Lake cause swimmer’s itch?
While warmer conditions are when swimmer’s itch is most common, the water temperature itself isn’t why people get it. The rash is caused by parasites that often live inside ducks and geese. To avoid getting swimmer’s itch, try to swim in clearer, deeper parts of the lake and avoid swampy, muddy-looking areas.
Plan a Visit to Flathead Lake
With the sailing season in full swing, Flathead Lake is a great summer getaway for travelers wanting to spend some time out on the water. If you want to experience some of the best sailing between the Pacific and the Mississippi, try ASA sailing courses with Go Sail Flathead Lake!