Hail Blankets for Cars: Do They Help?

Yes, a bit, if the blankets are thick, laid over the roof, hood and glass, strapped down, and on the car before the hail starts. Against small hail they can take the edge off. Against large hail, or once wind gets underneath, they help far less, and any solid roof you can reach in time does the job better.

The short answer: when a blanket helps

A hail blanket is the simplest version of a hail cover. It can be a purpose-made thick pad, or what most people grab on a warning afternoon: moving blankets, old duvets, sleeping bags, heavy comforters. The principle is the same either way. Padding absorbs and spreads the hit from each stone, so less of it reaches the metal.

A blanket is worth putting on when:

• You cannot get the car under a roof before the storm arrives.
• The blankets are thick. Several layers beat one.
• You can secure them so wind cannot peel them off.
• There is time to do it safely. Before the hail. Never during.

A blanket will not do much when:

• The hail is large. Environment Canada says hailstones can reach grapefruit size. A duvet is not built for that.
• It blows off. A loose blanket in a gust is a sail, then a heap on the driveway.
• It is one thin layer. A bedsheet or a light throw adds almost nothing.

Think of a blanket as damage reduction for small to medium hail, done quickly with what you have. Done well, it beats nothing. Done badly, it can scratch the paint it was meant to protect. Here is how to do it well.

Thickness: stack it where the hail lands

Hail falls mostly from above, so the panels facing the sky take the most direct hits: the roof, the hood and the trunk lid. Those are the panels to stack first.

• Layer, do not spread. Two or three thick layers on the roof and hood beat one layer stretched over the whole car.
• Thick and soft beats big and thin. A folded moving blanket or a heavy duvet is worth more than a large, thin sheet.
• A tarp is a rain shell, not padding. On its own it adds almost nothing. Strapped over thick blankets, it can keep them from soaking through.
• Do not forget the glass. The windshield and rear window lean back toward the sky, and a sunroof faces straight up.

If you only have enough for part of the car, put it on the roof and windshield first, then the hood. Why those panels carry so much of the damage, and what it takes to fix them, is in hail damage on the hood or roof.

Securing it in wind, without scratching the paint

A blanket that stays put is worth ten that blow away. The trick is holding it down without anything hard touching the paint.

• Run straps under the car. Soft straps or rope passing beneath the vehicle, front to back and side to side, hold far better than anything tucked at the edges.
• Keep metal off the paint. Hooks, buckles and ratchets should sit underneath the car, not on a panel. Wrap anything hard that has to touch the body.
• Use the doors with care. Some people trap the blanket edges in closed doors. It helps, but check that every door still closes and latches fully.
• Do not open the windows to tie through. Rain follows the rope inside.
• Close the gaps. Wind gets in at the corners. Tuck or tie them so there is no loose edge to grab.

Once it is secure, get back indoors. A blanket you have to chase across the driveway in a storm is not worth the trip outside.

Wet weight: the problem nobody plans for

Blankets soak up water. If rain comes with the hail, a soaked moving blanket or duvet is far heavier than the dry one you laid down.

That extra weight does three things:

• It sags and slides. A heavier blanket pulls at the straps and can creep down the panels.
• It holds grit against the paint. Whatever dust was on the car is now pressed under a wet, heavy layer.
• It is hard to lift off cleanly. Which is exactly when people start dragging.

Two ways to plan around it. Put a waterproof layer over the top if you have one and can strap it down. And leave the blankets where they are until the storm has fully passed and you can take them off properly.

Protect the roof, hood and glass first

Short on blankets or short on time? Spend them where they matter most.

1. Roof. The largest flat panel facing the sky.
2. Windshield and sunroof. A dent is a repair. Broken glass lets water into the car and can keep it off the road until it is replaced.
3. Hood. Large, flat, and the first panel anyone looks at.
4. Trunk lid and rear glass.
5. Doors and fenders last. They stand side-on to falling hail, so they are lower priority unless wind is driving it at an angle.

That order gets you the most protection per blanket. Once the storm has passed, though, how you take the blankets off matters as much as how you put them on.

Never drag it across the paint

This is the one rule that decides whether the blanket helped or hurt.

After the storm, the outside of the blanket is wet and gritty, and the inside has been pressed against whatever dust was on the car. Pull it off in one long drag and you sand the clear coat with it.

• Unhook everything first. Straps, ties, door edges.
• Lift from the middle, so the blanket comes up rather than across.
• Fold the dirty side in as you go, so nothing falls back onto the paint.
• Shake it out away from the car, and dry it before you store it.

It takes an extra minute. It is the difference between a car with no new marks and a car with fine scratches across the roof that were not there before the storm.

What a blanket will not stop

Be honest with yourself about the limits.

• Big hail. When the Northern Hail Project surveyed the August 2024 Calgary storm, it found evidence of hail from ping-pong ball to golf-ball size. A blanket can soften the smaller end of that. At the larger end, expect damage anyway.
• Wind-driven hail on the sides, where blankets are thinnest or missing.
• Anything that means going outside once the hail has started. No blanket is worth that.

Blankets are the fallback. A roof is the plan. If you can reach covered parking before the storm arrives, that beats any blanket, and the options are ranked in where to park when a Calgary hail warning hits. If you want something purpose-built for next season, compare the options in car hail covers in Calgary.

Dented anyway? Get a baseline

Blankets reduce damage. They do not always prevent it. If the car came out of a storm with dents, or you want to know exactly what it carries before next season, book the free 30-minute scan at the shop in SE Calgary. A technician maps every panel under proper lighting, so you know what is there and what can come out without paint. Rather start from home? Send a few photos taken at a low angle with light running across the roof and hood.