To store a boat for winter, flush and drain the engine's cooling water, stabilize the fuel, change the oil and fog the engine, pull and charge the battery, drain every water system, clean and dry the hull and interior, then park it on its trailer under a breathable, strapped-down cover. At AA Personal Storage in Parowan, Utah, uncovered Boat/RV/Trailer parking starts at $30 a month for a 10x30 space (as listed in October 2026).
Parowan winters are long and cold, and a boat that comes off the water with even a cup of water in the engine block can crack before spring. This guide walks through the full winter storage process for outboards, inboards, and sterndrives, with notes on what a high-desert Iron County winter means for a boat parked outside. If you also have a camper, see our step-by-step guide on how to winterize your RV.
Winterize your boat before the first hard freeze, which in Parowan usually means by late October. Average lows drop below freezing in November, and a single cold night can freeze water left in an engine or livewell.
Parowan sits at about 6,155 feet. Long-term averages from the Western Regional Climate Center's Parowan station show average lows of about 34°F in October, 24°F in November, and around 16°F to 17°F in December and January. December through March each average roughly 10 to 11 inches of snow. That means:
Plumbing and engine blocks sit below freezing for weeks at a time, and strong high-elevation sun keeps fading gelcoat, vinyl, and canvas even in December.
Many Iron County boaters spend summer on Panguitch Lake, Yankee Meadow Reservoir, Sand Hollow, Quail Creek, or Lake Powell. Whatever water you run, plan your last trip so you have a dry afternoon afterward to winterize.
You need fuel stabilizer, fresh oil and filters, fogging oil, non-toxic marine antifreeze (propylene glycol, usually pink), a battery charger or maintainer, and a breathable, fitted boat cover. Most of it is sold at local auto and outdoor stores.
Also grab flushing muffs or a flush-port adapter, marine grease, moisture absorbers, steel wool for mouse-proofing, and wheel chocks and tire covers for the trailer. Never use automotive antifreeze in fresh-water systems or anything that drains into a lake.
Winterizing the engine means removing all water, stabilizing the fuel, replacing old oil, and coating the internal parts with fogging oil so they don't rust. The steps differ a little by engine type, so always check your owner's manual first.
| Step | Outboard | Inboard / Sterndrive |
|---|---|---|
| Flush with fresh water | Yes, with muffs or flush port | Yes, through the raw-water intake |
| Drain cooling water | Tilt down so it drains fully | Open block and manifold drain plugs, or fill with antifreeze |
| Stabilize fuel | Yes | Yes |
| Change engine oil and filter | Yes (four-stroke) | Yes |
| Change lower unit or drive gear oil | Yes | Yes (sterndrive) |
| Fog the engine | Yes | Yes |
| Grease fittings | Steering, tilt, and swivel | Gimbal bearing, steering, and drive |
Add fuel stabilizer to the tank, then run the engine for 10 to 15 minutes on the muffs or in the water so treated fuel reaches the carburetor or injectors. Follow your engine maker's advice on how full to leave a built-in tank. Many recommend nearly full to limit condensation, while some carbureted outboards are run dry instead.
Warm oil drains faster, and old oil holds acids and moisture that can pit engine parts over a long winter, so changing it in fall rather than spring is the safer move. Replace the oil filter at the same time.
Drain the lower unit or sterndrive gear oil and look at it. Milky or creamy oil means water got past a seal, and that's worth fixing before spring, because water in a gearcase can freeze and crack the housing.
This is the step that saves engine blocks. For an outboard, leave the motor tilted down for a while so the water drains from the powerhead and lower unit. For an inboard or sterndrive, open every block, manifold, and water pump drain plug your manual lists, or circulate non-toxic antifreeze through the cooling system.
With the engine running, spray fogging oil into the air intake until it starts to smoke heavily and stalls, or follow your manual's method. On some engines you remove the spark plugs and spray into each cylinder instead. Fogging coats the cylinder walls so they don't rust over winter. Finish by greasing the fittings your manual lists.
Remove the battery, charge it fully, and keep it somewhere cool, dry, and above freezing on a maintainer. A fully charged battery resists freezing far better than a run-down one, which can freeze and crack in a Parowan cold snap.
If you leave the battery in the boat, charge it all the way, turn the battery switch off or disconnect the negative cable, and check it once a month.
Drain every system that holds water: livewells, baitwells, washdown pumps, fresh-water tanks, sinks, showers, and the head. Then pump non-toxic antifreeze through anything you can't fully drain.
Wash the hull and deck, dry the interior completely, and remove anything that holds moisture or food. A clean, dry boat is far less likely to grow mildew or attract mice over the winter.
Yes, if the boat is stored outdoors. A breathable, fitted boat cover blocks most sun, snow, and dust, while a plain plastic tarp traps moisture and rubs the finish whenever the wind moves it.
Tips for a cover that survives a Parowan winter:
For a deeper look at the roof-versus-open-sky question, read covered vs. uncovered RV storage. The same pros and cons apply to boats.
Most boats spend the winter on their trailer, so the trailer needs care too: grease the hubs, inflate the tires, chock the wheels, and check the lights before you park.
AA Personal Storage in Parowan, Utah rents outdoor, uncovered Boat/RV/Trailer parking: a 10x30 space for $30 a month and a 12x40 space for $40 a month, as listed on our Rent page in October 2026. The 12x40 was on a waiting list at that time.
| Space | Size | Monthly rate (Oct 2026) | Availability (Oct 28, 2026) | Good for |
|---|---|---|---|---|
| Boat/RV/Trailer Parking | 10 x 30 ft | $30 | Only 2 left | Most fishing boats, ski boats, and pontoons on their trailers |
| Boat/RV/Trailer Parking | 12 x 40 ft | $40 | Waiting list | Larger boats, long trailers, or a boat plus extra length |
Measure the full length of your boat on its trailer, from the hitch coupler to the back of the motor or swim platform, before you pick a size. A boat that's 20 feet long can measure several feet longer once you add the trailer tongue and an outboard.
Why boat owners in Iron County store with us:
Keep in mind that all of our Boat/RV/Trailer parking is uncovered and the parking spaces are not paved, so a good cover and wheel chocks matter. Vehicles and boats go in outdoor parking only, not in enclosed units. If you have gear to keep out of the weather, such as life jackets, skis, tubes, or fishing tackle, a small enclosed unit works well. Our 5x10 storage unit rents for $40 a month as listed in October 2026. You can also add tenant protection to your rental.
In spring, reverse the process: reinstall and test the battery, replace the drain plugs, check the gear oil and belts, flush the antifreeze from the water systems, and run the engine on muffs before your first trip. Check for mouse nests under the console and in the engine compartment, too.
Yes, if you winterize it first. Drain all water from the engine and plumbing, stabilize the fuel, remove or maintain the battery, and use a breathable, fitted cover strapped down tight. At AA Personal Storage in Parowan, Utah, all Boat/RV/Trailer parking is outdoor and uncovered, starting at $30 a month.
At AA Personal Storage in Parowan, Utah, about 20 miles north of Cedar City, uncovered boat parking costs $30 a month for a 10x30 space and $40 a month for a 12x40 space, as listed in October 2026. Rentals are month to month, with 24/7 access and video surveillance.
Water left in the engine block, manifolds, or lower unit can freeze, expand, and crack metal parts, which can mean a costly repair or a new engine. Untreated fuel can also go stale and gum up the fuel system, and a neglected battery can freeze and fail during a Parowan winter.
Yes, use a smart charger or battery maintainer, not a basic trickle charger that can overcharge. The best option is to remove the battery and keep it somewhere cool, dry, and above freezing. If it stays in the boat, charge it fully, switch it off, and check it monthly.
Many engine makers recommend a nearly full tank treated with fuel stabilizer, which limits condensation inside the tank. Some carbureted outboards are run dry instead. Follow your owner's manual. Loose gas cans and spare propane tanks aren't allowed at AA Personal Storage, so take them home.
Both work. A fitted, breathable cover is reusable and easier to remove for a winter visit. Shrink-wrap seals tighter and sheds heavy snow well, but it costs money every year and needs vents to prevent mildew. Avoid plain plastic tarps, which trap moisture and rub the finish in the wind.
Ready to park your boat for the season? Rent boat parking in Parowan online in a few minutes with no meeting, or reserve a space with a $50 deposit that is credited to your move-in and holds it for 25 days. Want to compare enclosed units for your gear? See our full storage unit size guide.
Questions? Call AA Personal Storage at (435) 447-4777 or email hello@aapersonalstorage.com. We're at 450 N 600 W, Parowan, UT 84761, just off I-15, and open 24/7.
