Warm Halloween Costumes: A Layering Guide That Actually Works

Yes, you can stay warm in a Halloween costume, though not by buying a thicker one. It's layers: something snug against the skin first, the costume over it, a coat last. We sell Morphsuits, so it would be easy to tell you one keeps you warm alone. It doesn't. It's 125GSM+ breathable fabric, built for comfort through a long party, not insulation. Worn first, under a bigger costume, that same suit is the base layer that carries a cold October night.

• Start with a base layer
• Choose full coverage over skin-baring
• Inflatable costumes run warm by design
• Or skip the layering: a fleece animal onesie
• What not to do
• Frequently asked questions

Start with a base layer

A base layer works by sitting close to your skin without restricting you, so nothing can get between it and you and steal the heat. That needs a close fit and a fabric that breathes, which is why a solid-colour Morphsuit does the job and a jumper doesn't: 91% polyester, 9% elastane, 4-way stretch, and 125GSM+ breathable fabric built for comfort rather than bulk. It goes on under a bigger costume or your own coat without adding any at all. If you're still deciding what goes over the top, our Best Halloween Costumes UK 2026 guide is the shortlist.

Every solid colour uses the same fabric, so pick by look, not warmth: black is the one that vanishes most completely under a darker costume if you want it invisible. What you put on under the Morphsuit matters more than which colour you pick: skip the plain cotton t-shirt. Cotton holds sweat rather than moving it away from your skin, so it can leave you colder once you stop dancing, not warmer.

The base layer: a solid-colour Morphsuit

Our white Morphsuit is 91% polyester, 9% elastane with double zips, in four adult sizes from M to XXL. The size guide on the product page works from your height and chest measurement together, not your usual clothing size, so check both before you order. Wear it on its own as a fancy dress costume, or wear it first: it's one stretch layer covering you from head to foot, so a bigger costume, a mask or a coat goes straight over the top with nothing bare underneath. There's nothing in the pack except the suit, and that's the point. Hand wash it cold and air dry it, never the machine.

Choose full coverage over skin-baring

Bare skin is where the heat goes, and a costume assembled from separate pieces leaks at every join: the waist, the wrists, the ankles, and again every time you raise your arms. The full-body Morphsuit styles in our Halloween costumes range close all of those by not having any. One piece, two zips, head to foot.

The caveat we'd rather say out loud than have you find out at 9pm: covering your head, with a full hood or a mask, closes off one of the places your body dumps heat. So a full-coverage costume can run hotter than you expect once you're moving, not colder. Decide that before you put a heavy coat over the top and spend the night sweating in it.

Full coverage in one piece: the Zombie Morphsuit

Our Zombie Costume Morphsuit is a print Morphsuit in the same 91% polyester, 9% elastane build as the base-layer suit above, with a full hood and double zips, one size fits most adults. Zip it up and there's no bare wrist or ankle left for the October air to find, and the costume and the coverage are the same decision. One thing to weigh before you order: a one-size cut has no larger band to move up into, so if you want something underneath this one, keep it thin. Hand wash cold and air dry, same as the white suit.

Inflatable costumes run warm by design

An inflatable costume is warm almost by accident. The fan that holds its shape also keeps a cushion of moving air between you and the shell, and trapped air insulates the same way a duvet does. The catch is that this warmth is powered, and it lasts exactly as long as the batteries do. That makes an inflatable the pick for an evening standing in one place, a party or a garden, rather than an hour of walking between doors with a bag of sweets.

Warm by design: the Giant Inflatable Alien Costume

Our Giant Inflatable Alien Costume runs a high-powered fan with over four hours of battery life, on 4 x AA batteries you supply yourself, and the elasticated seals hold both the shape and the warm air in as you move. It's 100% polyester, one size fits most, and worn correctly it looks like the alien is carrying you off. Take the fan pack out first, then it's a sponge wipe, not a wash. For the full range, see Best Inflatable Costumes Ranked for 2026.

Or skip the layering: a fleece animal onesie

A fleece onesie is the only costume here that's warm with nothing running and nothing underneath. Our own product page puts it plainly: made from 100% polyester fleece, so it stays warm and cosy throughout the night. No batteries, no base layer, no sizing up to leave room for one. It's the pick if you're on the door handing out sweets for two hours, or if the party is half indoors and half in somebody's back garden.

Warm on its own: the Green Dinosaur Onesie

Our Green Dinosaur Onesie Costume is a hooded one-piece with felt teeth, back spikes and an attached tail, in three adult sizes: M, L and XL. The hood is the part that earns its place on a cold night, and because it's attached, it isn't the thing you leave in the car. Fleece is the fabric people assume they can put through a wash. This one you can't: cold hand wash, air dry flat, no machine and no tumble dryer.

What not to do

Halloween 2026 falls on a Saturday, so most people will be out for longer than on a weeknight. UK October days reach an average of 13°C nationally, dropping to about 6°C overnight, on the Met Office's 1991-2020 UK climate average (Met Office UK and regional series). That's a night to plan the layers for, not one to solve at the front door with whichever coat is on the hook. Four things not to do:

• Don't reach for one heavy coat. A single thick layer over a costume changes the whole shape of it and can't be adjusted once you're too warm indoors. Outdoor-gear guidance recommends a base, mid and outer layer, because you can add or remove one at a time as conditions change (REI Co-op); one heavy coat can't flex the same way.
• Don't skip sizing up. If a base layer is going underneath, order the outer costume one band larger than you'd normally take. Sizing up only works if the band you're sizing up from is a real number, and every costume is measured across 30+ points, so the figure on the product page describes the garment. The room for your base layer is what you add on top of it. There is nowhere to put a Morphsuit under a costume that already sits close on its own.
• Don't wear cotton as the base layer. That includes the hoodie you were going to put on under the costume. Cotton soaks up sweat and dries slowly, so once you stop moving or the night turns damp, it can leave you colder than wearing nothing under there at all. A close-fitting synthetic layer, a Morphsuit included, doesn't have that problem.
• Don't assume "full coverage" always means "cooler head too". Covering your head with a mask or hood traps in heat your body would otherwise release there, so a full-coverage costume can run warm rather than cold once you're dancing or walking. Layer for the temperature you'll actually be at, not just the one on the forecast.

Frequently asked questions