A jet ski stored outside for any length of time needs more than a cover thrown over it and a hope for the best. Personal watercraft are compact but expensive — a new Yamaha WaveRunner or Sea-Doo costs $10,000 to $20,000 or more — and they’re exposed to the same UV radiation, salt air, humidity, and pest pressure as any larger boat. The difference is that jet skis are easier to damage quickly because their compact size concentrates the environmental impact.

This guide covers everything you need to store your jet ski outside safely — whether you own a single stand-up PWC, a sit-down runabout, or a three-seater touring model. We’ve written it with Florida’s conditions specifically in mind, but the core prep steps apply anywhere. The checklist at the end is printable and designed to be used every time.

1. Flushing the engine — the most important first step

If you’ve ridden in salt water, brackish water, or any water with biological content — which covers virtually all riding in Northeast Florida — flushing the engine cooling system is the single most important step in jet ski storage prep. Salt deposits in the cooling passages cause rapid internal corrosion and restrict water flow on the next start, potentially causing overheating on your first ride of the season.

How to flush a jet ski engine correctly

Most modern jet skis have a dedicated garden hose flush port — typically labelled “Flush” and located near the engine compartment or on the hull. Connect a garden hose (do not turn the hose to full pressure — low to medium flow is correct), then start the engine and let it run for a minimum of 3 minutes while fresh water flushes through the cooling system. The water exiting the tell-tale stream should run completely clear before you stop.

Post-flush fogging for storage over 30 days

After flushing and while the engine is still running, spray marine fogging oil into the air intake for approximately 5–10 seconds. This coats the internal engine components with a protective oil film that prevents corrosion during the storage period. Shut the engine off immediately after fogging — the engine will smoke briefly as the oil burns off on the next start, which is normal.

2. Fuel system preparation

Jet ski fuel systems are particularly susceptible to ethanol-related problems because the fuel tanks are relatively small and the entire system — tank, lines, injectors or carburettor — is contained in a compact space that gets very hot during storage in the sun.

Fill and stabilise

Fill the fuel tank to approximately 95% capacity — enough to minimise the air space that allows condensation and ethanol phase separation, but leaving a small allowance for thermal expansion in summer heat. Add an ethanol-specific marine fuel stabiliser (Star Tron Enzyme Fuel Treatment is widely used for jet skis) at the full recommended treatment rate. Run the engine on the flush connection for 3–5 minutes after adding the stabiliser to ensure it circulates through the entire fuel system.

Check the fuel lines and primer bulb

Inspect the fuel lines for any cracking, hardening, or weeping where the line meets the fitting. Check the primer bulb (if fitted) for firmness — a soft or spongy bulb indicates a fuel line or check valve issue. Replace any damaged fuel lines before storage to avoid finding a fuel leak on your first start of next season.

3. Battery care during storage

Jet ski batteries are smaller than boat batteries and discharge faster. A jet ski left with a connected but unmaintained battery will typically have a dead battery within 3–4 weeks — and a deeply discharged battery may not accept a charge or hold charge reliably after recovery.

• Fully charge the battery before storage using a proper marine battery charger — not a car battery charger which delivers too high an initial charge rate for small PWC batteries
• Connect a smart battery maintainer (Battery Tender Junior or NOCO Genius 1 are appropriately sized for PWC batteries) to keep it at full charge during storage — this is the ideal option
• If a maintainer isn’t available: remove the battery from the jet ski, clean the terminals, apply terminal protector spray, and store it in a cool dry location. Check voltage monthly — should stay above 12.4V for a 12V system
• Most modern Sea-Doo and Yamaha models use a sealed AGM battery — these handle storage better than flooded lead-acid but still benefit from a maintainer for periods over 60 days
• Check your owner’s manual for the specific battery type and any model-specific storage recommendations

4. Hull and exterior cleaning

The hull of a jet ski takes a harder beating per square foot than most boats — it sits lower in the water, gets dragged up on beaches, and operates in shallower water with more biological contact. Thorough hull cleaning before storage prevents permanent staining and makes the next season’s prep dramatically easier.

Rinse immediately after the last ride

Rinse the entire hull, including the underside and intake grate, with fresh water immediately after the final use. Remove any weeds, grass, or debris from the intake grate — this is a legal requirement in many Florida counties to prevent the spread of invasive aquatic plants, and it also prevents biological matter from decomposing in the intake during storage.

Full wash and wax

Wash the hull with marine soap and a soft brush or microfibre cloth. Pay particular attention to the waterline, the hull seams, and any non-skid surfaces where biological matter accumulates. Apply a UV-inhibiting marine wax or hull protectant to all fibreglass surfaces above the waterline — in Florida’s UV environment this is essential for protecting gel coat colour and gloss during storage.

Stainless hardware and fittings

Rinse and dry all stainless steel hardware — cleats, handles, mirrors, and rearview attachments. Apply a stainless protectant to prevent the tea-staining and pitting that stainless develops in salt air over a storage period. Check the jet pump wear ring for any visible damage or foreign object impact — this is the right time to identify issues before next season.

5. Interior compartment and drain plug

The storage compartments inside a jet ski — the bow storage, the rear storage, and the battery compartment — are enclosed spaces that accumulate moisture and become mould traps during outdoor storage in Florida’s humidity. A few simple steps prevent this entirely.

Drain all compartments

Open all storage compartment lids and allow them to air and drain completely. Remove everything from the compartments — ropes, safety equipment, personal items. Wipe all compartment surfaces with a dry cloth. Leave the lids open for 30 minutes after washing to allow the interiors to dry fully before storage.

Remove the hull drain plugs

Every jet ski has at least one hull drain plug — often two. Remove all of them before outdoor storage. This allows any rain water or condensation that enters the hull to drain out rather than accumulate. Store the drain plugs in the bow compartment where they’re easy to find and reinstall before the next launch.

6. Choosing and fitting the right cover

A quality PWC cover for outdoor storage needs to satisfy three requirements simultaneously: UV protection, breathability to prevent moisture trapping, and a secure fit that resists wind. In Florida’s summer conditions, cutting corners on any of these creates real problems.

PWC-specific covers vs. generic covers

Purchase a cover specifically designed for your jet ski’s make, model, and year if at all possible. A generic or universal cover that doesn’t fit correctly will flap in wind, abrade the hull surface through constant movement, and allow water ingress at the edges. A model-specific cover fits snugly, has the correct bow and stern profile, and stays in place through Florida thunderstorms.

What to look for in a Florida-suitable PWC cover

• Breathable material: Essential in Florida. A non-breathable cover traps humidity inside and creates the conditions for mould on the seat and interior surfaces. Look for covers specifically described as breathable or ventilated.
• UV rating: Should block 95%+ of UV radiation. Florida’s UV destroys cover materials that aren’t UV-rated within a single summer — they become brittle, fade, and tear at stress points.
• Belly straps and tie-downs: Multiple securing points prevent the cover from billowing and shifting in wind. At minimum, two belly straps and a nose cinch strap.
• Mirror and handle cutouts: A properly fitted cover should have cutouts or reinforced areas for your specific model’s handles and mirrors — forcing generic covers over these points creates tears and stress points.

Fitting the cover correctly

Fit the cover on a clean, dry hull. Work systematically from the bow to the stern, ensuring the cover sits properly in all the hull contours before securing the straps. Tighten every strap until the cover has no loose material — even a small loose area will flap in wind and cause abrasion. After securing, run your hand over the entire surface checking for any areas with slack.

7. Trailer and stand preparation

Most jet ski owners store on the manufacturer trailer, but some use a purpose-built PWC stand or dock cradle. Either way, the storage platform deserves its own prep.

8. UV and corrosion protection for Florida storage

A jet ski stored in Florida’s summer sun without UV protection will look several years older when you retrieve it. The seat material, gel coat, plastics, and any rubber components all degrade rapidly under continuous UV exposure.

Seat and upholstery

The PWC seat is the most UV-vulnerable component on most jet skis — the vinyl or hypalon material becomes brittle, fades, and develops surface cracking under sustained UV exposure. Apply a UV protectant (303 Aerospace Protectant is the widely recommended product for marine vinyl) to the seat surface before fitting the cover. Even under a UV-rated cover, this base layer protects against UV that penetrates the cover material.

Engine compartment

Open the engine compartment lid and spray all electrical connections, the fuse box, the battery terminals, and any exposed metal surfaces with a corrosion inhibitor such as Corrosion Block or Boeshield T-9. Close the lid securely. Salt air infiltrates engine compartments even when closed — the corrosion inhibitor creates a barrier that slows the process significantly.

Handlebars, mirrors, and plastic trim

Apply UV protectant to all plastic trim, handlebars, mirror mounts, and any rubber grip material. These components are typically left uncovered even under a full body cover at the edges — they receive more UV exposure than the hull centre and degrade faster without treatment.

9. Florida-specific jet ski storage tips

Florida jet ski storage has specific considerations that standard guides don’t address. Here are the ones that matter most for Jacksonville-area owners.

• Pest prevention is year-round: Ants, cockroaches, and wasps are active in Florida through all storage months. Check all compartments for pest entry points and seal any gaps. Place pest deterrent strips or roach bait in exterior compartments. A wasp nest in the engine compartment discovered when you open the lid is both dangerous and damaging.
• Aquatic invasive plant regulations: Florida Fish and Wildlife Conservation Commission requires that all aquatic vegetation be removed from watercraft before transportation. Always clean the intake grate of any plant material when haul-out — this is both a legal requirement and good practice to prevent material decomposing in the intake during storage.
• Ethanol fuel is especially problematic in Florida heat: Fill and treat the fuel tank on the same day you haul out — don’t leave an untreated partial tank sitting in a hot garage or storage facility for even a week before adding stabiliser.
• The humidity-mould timeline is compressed: In Jacksonville summer heat, mould can develop on a jet ski seat in as little as 7–10 days in a poorly ventilated cover. A breathable cover and at least one DampRid bag in an interior compartment are non-negotiable.
• Position with the bow slightly elevated: Position the trailer with the bow higher than the stern to allow drainage of any water that enters during rain. Even with drain plugs removed, the low-point drainage depends on the trailer angle.

10. Getting your jet ski back on the water

Before the first ride of the season, work through a pre-launch inspection rather than going straight from the storage lot to the ramp. Catching a problem at the facility takes 20 minutes — catching it at the ramp means a wasted trip.

Pre-launch inspection sequence

• Reinstall all drain plugs — confirm visually before launch
• Check fuel level and smell for any unusual odour that might indicate fuel degradation
• Reconnect the battery and test the start sequence on the flush connection before trailering
• Check the wear ring by spinning the impeller by hand — should turn freely without catching
• Inspect the jet pump intake grate for any damage or blockage
• Test all electronics, including the kill switch tether
• Check tyre pressure and wheel bearing condition on the trailer before the tow

11. Complete jet ski outdoor storage checklist

Engine and fuel

• Flush engine cooling system via flush port for 3+ minutes until water runs clear
• Fog engine with marine fogging oil (storage over 30 days)
• Fill tank to 95% and add ethanol-specific marine fuel stabiliser
• Run engine 3–5 mins on flush connection to circulate stabilised fuel
• Inspect fuel lines and primer bulb for cracking

Battery

• Fully charge battery using correct PWC-rated charger
• Connect smart battery maintainer, or disconnect and remove battery
• Clean terminals and apply terminal protector spray

Hull, exterior, and interior

• Remove all debris and aquatic vegetation from intake grate
• Rinse entire hull including underside with fresh water
• Wash hull with marine soap; apply UV-inhibiting marine wax to fibreglass
• Remove all hull drain plugs; store in bow compartment
• Open and dry all storage compartment interiors; remove all contents

UV and corrosion protection

• Apply 303 Aerospace Protectant to seat, plastic trim, and handlebars
• Apply corrosion inhibitor to engine compartment electrical connections
• Fit model-specific breathable UV-rated PWC cover; secure all straps

Trailer

• Rinse trailer with fresh water; inspect frame for corrosion
• Inspect and repack wheel bearings if used in salt water
• Inflate tyres to maximum cold pressure; fit tyre covers
• Chock wheels and fit coupler lock