Best (Warmest) Swimming Lakes In Washington State

Recently, an old friend of mine from college told me that, after years of talking about it, he and his family are going to take a road trip through Washington this summer.

They live in Arizona’s Sonoran Desert, which means the only swimming water they normally have access to are the manmade lakes in the mountains. Naturally, they want to swim in some warm water during their visit.

He then asked if I knew a lot about swimming lakes in Washington. I told him I wasn’t intimately familiar with every single lake and I’d probably miss one or two good ones but could still come up with a pretty good list.

He laughed and said that even five or six would be fine since they’ll only be here for about a week. I told him I’d send him an email so that he could show his wife and then could figure out which works best for their plan.

Let’s start by talking a little bit about the lakes in Washington and then we’ll get into our list of the warmest ones.

Background on Washington Lakes and What Makes Them Warm

Although the Pacific Northwest in general is more commonly associated with trees and mountains, there are plenty of lakes here, too. In fact, there are over 8,000 named lakes within the state of Washington!

Of these 8,000, however, most of them are pretty cold and not very comfortable for swimming. As a general rule, the ones on mountains are usually pretty cold, as they’re often made up of water run-off from glaciers.

So, how you can find a warm swimming lake? The easiest way is to find out how deep the lake is. A deeper lake has more water and therefore will take a lot more heat from the sun to warm up than one that’s more shallow.

You’ll also want to find a lake that’s closer to sea level. The lakes you’ll find on mountains tend to be colder, partly because most of them are made by runoff from glaciers and partly because they’re so high up.

Remember the end of the first Iron Man movie when the bad guy’s suit freezes because he flew up too high? It’s like that but with cold water instead of a robot suit. Anyway, let’s get into some of the warmer lakes you’ll find in the state of Washington.

Lake Sammamish

About eight miles east of Seattle, you’ll find beautiful Lake Sammamish in a State Park of the same name. It’s not the first lake that most people think of but it’s one of my favorites because of how warm it gets.

The main reason for this is that its deepest point is barely over 100 feet. The lake is eight miles long and about a mile and a half wide, which means you’ll find plenty of beach to enjoy.

In addition to swimming, popular activities here include jet skiing, fishing, tubing, and wakeboarding, plus a whole lot more.

Cranberry Lake

Cranberry Lake is located on the northern shores of Deception Pass State Park on Whidbey Island, near the Canadian border. You can drive up and take the bridge from Fidalgo Island or take a Washington State Ferry from Alaska Street in Seattle.

This is the perfect place for a dip on a warm summer day because it’s a shallow lake with a designated swimming area and it has an elevation of about eight feet. There are plenty of trees, too, which will help protect against the wind.

In the park, you’ll also find fishing, a boat launch ramp, changing rooms, and 30 miles worth of hiking trails. It’s also worth noting that part of the park is on Fidalgo Island as well.

Sun Lakes

Near the Grand Coulee Dam in Central Washington’s Grant County, you’ll find the beautiful Sun Lakes in Sun Lakes-Dry Falls State Park. With just under 14 miles worth of shoreline, you’ll easily be able to find a spot to leave your stuff while you swim.

As the name implies, there are multiple lakes to choose from and they’re all relatively warm. You can enjoy a relaxing dip in any one of them and, if it gets too crowded, you can simply move to one of the more secluded options.

You’ll also be able to enjoy fishing, boating, waterskiing, 15 miles of hiking trails, and more. Sun Lakes Resort has a golf course and camping options as well. Dry Falls is also definitely worth a look while you’re here.

Deep Lake

Just south of Olympia in Millersylvania State Park, you’ll find a perfect place to swim at Deep Lake. You may be wondering why it would be listed here despite my saying in the intro that shallow lakes are warmer.

The answer is that, despite the name, the lake reaches a maximum depth of 17 feet. No one really knows why got its name. Despite the mystery, it’s a great place to relax in some warm, relatively shallow water!

The eastern shore is occupied by an RV resort park, so you’ll probably want to start on the western part of the shore and find a quiet place. It’s also a great fishing spot as it is stocked with rainbow trout. There are also a few other naturally occurring fish.

Pine Lake

In Sammamish about 20 miles east of Seattle, Pine Lake in the city park of the same name is the perfect place for a summertime swim. It is about 40 feet deep at its lowest point but has an average depth of about 20 feet.

The lake is very popular in summer and many events are held here throughout the year. If you’d like to avoid crowds, I’d suggest coming during off-peak hours. It is open from 6:30 to dusk in the summer and 7:30 to dusk in the winter.

It is also a popular fishing spot, with trout and bass being stocked by the state Department of Fish and Wildlife. There is a designated section for shore fishing on the eastern portion, so you’ll want to swim on the western side.

Lake Chelan

Lake Chelan in Central Washington’s county of the same name is a rather surprising entry on this list because, unlike the rest, it isn’t shallow at all. In fact, its maximum depth of 1,486 feet makes it the third-deepest in the United States!

However, it still gets pretty warm because it’s only about a mile and the surrounding area is very hot and dry, with the southern area averaging just over 11 inches of rainfall per year.

Its relative isolation makes it a great place to enjoy swimming, fishing, and hiking. There are also many wineries in the area but I’d recommend enjoying the water first, as alcohol and swimming do not mix.

Lake Ozette

In northwestern Washington’s Olympic National Park a few miles from the Pacific Coast, Lake Ozette is the perfect secluded location for a swim. It is the largest unaltered lake in the state and has a maximum depth of 331 feet.

It is less traveled than most of the other lakes on this list because of its remote location. Most other attractions in Olympic National Park are at least an hour’s drive away, making Ozette a great place to avoid crowds.

There are many hiking trails near the lake and a campground operated by the US Forest Service. One of these is a boardwalk trail that leads to the Ozette Indian Petroglyphs at Wedding Rock.

Final Thoughts

Of the over 8,000 lakes in the state of Washington, it can be difficult to find one that will be warm enough to swim comfortably in. That being said, there are still a few great options for a dip on a hot summer day.

If you come across a lake you’d like to swim in but aren’t sure what the temperature will be, find out how deep it is. There are exceptions, of course, but a shallow lake at a lower elevation will tend to be much warmer than most other options.

No matter which lake of these lakes you choose, you’ll be sure to have a wonderful time swimming in our warm lakes in the state of Washington. We can’t wait to see you soon!