pool-service

When Should You Close Your Pool in Minnesota? Timing, Water Temperature, and What a Late Close Costs You

When to close your pool in Minnesota: the 60-degree water rule, closing dates by region, what a professional closing includes, and what it costs in 2026.

When Should You Close Your Pool in Minnesota? Timing, Water Temperature, and What a Late Close Costs You

The right time to close a pool in Minnesota is when the water temperature holds below 60 degrees for a week straight, and in most of the state that happens between the last week of September and the middle of October. Closing earlier than that invites algae under the cover, and closing later than that risks a hard freeze on plumbing that is still full of water.

The date on the calendar matters less than the thermometer. A warm September in the Twin Cities can keep pool water above 65 degrees into the first days of October, while a cold snap in Duluth or Bemidji can drop it below 55 by mid-September. The 60-degree rule works because algae growth slows to almost nothing below that temperature, and the chemicals you add at closing stay effective through the winter.

Professional pool closing in Minnesota costs $250 to $500 in 2026 for a typical inground pool, and $150 to $300 for an above-ground pool. The price includes blowing out the lines, adding winterizing chemicals, and installing the cover. The first hard freeze in the Twin Cities usually arrives in the first or second week of October, which is why the good pool companies are booked solid from mid-September on.

Why 60 Degrees Is the Line

Algae is the reason to wait. Chlorine breaks down faster in warm water, and a pool closed at 70 degrees with a solid cover on top becomes a dark, warm, unchlorinated pond for the two or three weeks before the water cools. Opening that pool in May means a green swamp and a $200 to $400 chemical bill on top of the opening fee.

Freezing is the reason not to wait too long. Once nighttime lows drop into the 20s, water left in the skimmer, the return lines, or the pump housing expands as it freezes, and a cracked skimmer or a split pipe under the deck is a $500 to $3,000 repair the following spring. Pool plumbing does not have to be full to crack; a few inches of standing water in a low spot is enough.

The window between those two risks is narrow in Minnesota, often just two or three weeks. A pool thermometer and the ten-day forecast are the tools that matter, and once the water sits under 60 with no warm-up coming, it is time.

Closing Dates by Region

The Twin Cities metro, from Minnetonka to Woodbury and Lakeville to Blaine, usually hits the 60-degree mark in the last days of September or the first week of October. The first frost arrives around the second week of October in an average year, so a closing scheduled between October 1 and October 10 is the sweet spot for most metro pools.

Rochester, Mankato, and the southern tier run a few days behind the metro, and pools there can often stay open through the first week of October in a mild year. St. Cloud and the central part of the state run a few days ahead.

Duluth, Brainerd, and the northern half of Minnesota see water temperatures drop below 60 as early as mid-September, and the first frost can come in the last week of September. Pool owners in the north should plan for a closing between September 15 and October 1, and should not count on a warm spell to buy time.

The far north, from Bemidji to International Falls, has the shortest season in the state. Many pools there close by mid-September, and the pool companies that serve the region often start their closing schedule the week after Labor Day.

What a Professional Closing Includes

A standard closing starts with balancing the water: pH between 7.2 and 7.6, alkalinity in range, and calcium hardness adjusted so the water does not etch plaster or scale tile over the winter. The technician then shocks the pool, adds a winter algaecide, and often a stain and scale preventer.

The water level is lowered below the skimmer and returns, usually 4 to 6 inches on a pool with a mesh safety cover and 12 to 18 inches on a pool with a solid cover, and the lines are blown out with a compressor and plugged. The pump, filter, and heater are drained, and the pump and any removable equipment are stored indoors if the owner wants.

The cover goes on last. A mesh safety cover anchored to the deck is the standard in Minnesota because it handles snow load and lets meltwater through, and a solid cover with a pump on top is the alternative. Winter covers on above-ground pools are secured with a cable and often an air pillow in the middle to take the ice pressure off the walls.

Above-Ground Pools

An above-ground pool closing in Minnesota costs $150 to $300 and takes about an hour. The steps are the same in principle: balance, shock, lower the water below the skimmer, remove and store the pump and filter, plug the return, install the air pillow, and secure the cover. Some owners do this themselves with a $30 winterizing kit and a shop vacuum.

The one step that matters most on an above-ground pool is the air pillow. As the pool surface freezes, the ice pushes outward, and without a pillow to absorb that pressure the walls can buckle. Replacing a pillow is $15; replacing a wall is the price of a new pool.

Heated Pools and Hot Tubs

A heated pool can stay open longer, and some owners in Edina or Eden Prairie run the heater through October to squeeze out a few more weekends. The cost is real, since heating a pool in Minnesota in October runs $300 to $600 a month in gas. The heater also has to be fully drained at closing, and a heater that is winterized wrong is the most expensive component to replace.

Hot tubs and spas in Minnesota often stay open all winter. If you close one, it needs the same line blow-out and a full drain of the jets and pump, and a professional spa winterization runs $150 to $300.

Doing It Yourself

A do-it-yourself closing costs $60 to $120 in chemicals and plugs, plus an air compressor or a shop vacuum with a blower port to clear the lines. The lines are the hard part. Every return, the skimmer line, and the main drain line have to be blown until they bubble, then plugged before water flows back, and a missed line is a cracked pipe in April.

The filter is the second place things go wrong. A sand filter needs its drain plug removed, a cartridge filter needs the cartridge pulled and the housing drained, and a DE filter needs to be backwashed, disassembled, and drained. Water left in any of them freezes and cracks the tank.

For a first-year pool owner, paying $300 for a professional closing and watching the process is a reasonable way to learn. The technicians who close pools in Minnesota do hundreds a season and know where the water hides.

Booking a Closing

Pool companies across the Twin Cities open their fall schedules in August and fill the late September and early October slots first. Booking by Labor Day gets you a choice of dates, and booking in late September often means taking whatever remains, which may be earlier than the water temperature calls for.

Ask what is included. Some companies quote a base price and add chemicals, cover installation, and equipment storage separately, which can turn a $275 quote into $450. A full-service closing should list every step, and the good ones will also note anything they see that needs repair before spring.

Many companies discount a closing when it is bundled with a spring opening or a monthly service plan. You can compare pool companies in your area in our Minnesota pool service directory, and our home and yard blog has more on pool opening, cover choices, and what to check before buying a house with a pool.

Frequently Asked Questions

Can I close my pool in Minnesota before Labor Day?

You can, but the water is usually too warm and algae will grow under the cover. Unless you are leaving town for the fall, waiting until the water sits below 60 degrees saves chemicals and work in the spring.

What happens if I wait too long to close my pool?

A hard freeze with water still in the skimmer or lines can crack them. In the Twin Cities the first freeze typically arrives in early to mid October, so a pool still open on October 15 is running out of margin.

How low should I drain the water for winter?

Four to six inches below the skimmer for a mesh safety cover, and 12 to 18 inches for a solid cover. Draining further than that on an inground pool risks the shell lifting if groundwater is high.

Do I need to close a pool with a mesh safety cover differently?

The steps are the same, but the water level stays higher because meltwater passes through the mesh. Expect to add a little water and rebalance in spring, since snowmelt dilutes the chemicals.