What to wear in 40 degree weather

30 September 2026 · 8 min read

At a feels-like 40°F (4°C), wear a long sleeve, a hoodie and a puffer vest, with jeans and boots. No coat. But 40°F is the last degree before one, and the lightest breeze is enough to push a 40 degree forecast over that line.

Most guides to this temperature put you straight into a wool coat or a puffer, and Google's own AI answer suggests a jacket or coat too. We ran 40°F through Comfie's outfit engine instead. The coat turns out to be right most mornings, but for a reason none of those guides mention.

What to wear at 40 degrees, by feels-like

At a feels-like 40°F (4°C), wear a long sleeve, a hoodie and a puffer vest, with jeans and boots. That's three layers on top and no coat. At 39°F Comfie's engine swaps the vest for a puffer jacket, the hoodie for a fleece, and adds a beanie. A 3 mph breeze is enough to cause that swap.

Every row below comes straight out of the engine, the same code that runs the demo on this site.

Swipe the table sideways for the rest of each row.

Look where 40°F sits. On the very bottom edge of vest weather, with the coat one degree below it.

Rather not check a table at 7am? The live demo does it from your city name, no download.

Forty is the last degree of vest weather

Comfie's engine gives every layer a warmth number and builds a stack that hits a target for your top half. A long sleeve, a hoodie and a fleece are worth 3 each. A puffer vest is 2. A puffer jacket is 4.

From 40 to 47°F (4 to 8°C) the target is 8. Long sleeve (3), hoodie (3), vest (2). Done.

At 39°F (4°C) the target jumps to 10, and the only sensible way to find two more points is to trade the vest for a puffer jacket. The engine also names a fleece instead of the hoodie. That's the same 3 points, so keep whichever one you own. The vest is no compromise: it's worth exactly what a light jacket is, and it leaves your arms free.

Three things change within three degrees of 40:

• Under 42°F (6°C), boots replace sneakers.
• Under 40°F (4°C), the vest becomes a puffer jacket.
• Under 40°F, a beanie arrives too.

Gloves wait until 35°F (2°C). So 40°F is a crowded spot, and a forecast that's off by a degree or two lands you in a different outfit.

A 40 degree forecast is rarely a vest day

The feels-like number folds wind into the temperature. The US wind chill formula, the one the National Weather Service has used since 2001, is steepest at low speeds, so the first few miles an hour take off the most. And 40°F is already standing on a band edge.

Swipe the table sideways for the rest of each row.

Read the first two rows. Still air to 3 mph costs about two degrees, and 3 mph is barely wind: you'd feel it on your face but not see it in the trees.

So a 40°F vest day needs air that is properly still. Any real breeze and you're in coat weather before you reach the end of the street. By 25 mph, a 40 degree forecast wants the same parka as a still 29°F morning.

It works in reverse too. A feels-like 40°F doesn't need a 40°F day. By the same formula, 43°F air in a 5 mph breeze feels like 40°F, and so does 45°F at 10 mph or 47°F at 15 mph. If your app shows two numbers, dress for the lower one. Feels like vs actual temperature explains why they drift apart.

One caveat: these figures use the NWS formula because anyone can check it. It only counts wind from 3 mph up and air at 50°F or colder, and your weather app may calculate feels-like a little differently, which at 40°F can be the whole decision. So look at the wind as well as the number.

Why most guides say a coat at 40

Because on most mornings they're right. It takes very little wind to turn 40°F into coat weather, and dead-calm air is the exception, not the rule. With a breeze the engine agrees with them: a puffer jacket, a beanie, and gloves once the wind reaches 10 mph.

Where they go wrong is making it the rule. A calm, dry 40°F afternoon in a puffer is two warmth points more than you need, and you'll be unzipping it by lunch. The vest exists for exactly that day. The coat side of the line, including why it sits at 39°F and not the 50°F most people guess, is covered in do I need a coat today.

Shoes, hat and gloves at 40 degrees

Boots. Sneakers only hold down to a feels-like 42°F (6°C).

Your head and hands depend on the wind again. A still 40°F needs neither a beanie nor gloves. The beanie comes in below 40°F, so the same 3 mph breeze that brings the puffer brings the beanie with it. Gloves follow under 35°F (2°C), which a 40°F day reaches at about 10 mph.

Below the waist, plain jeans. Comfie keeps them on with nothing underneath all the way down to 20°F (-7°C), because the warmth comes from the three layers on top. Is it jeans weather today follows denim across its whole range.

Rain and snow at 40 degrees

Rain doesn't change the warmth target. It changes the outer layer and what you carry.

• Any rain in the forecast. The vest becomes a light jacket, which is the same 2 points with sleeves, and an umbrella comes along. Even a 60% chance of a 3pm shower does this, because you leave the house in the morning.
• Rain all day. Still boots. Comfie only picks rain boots from 42°F (6°C) up, and plain rubber rain boots have no insulation anyway.
• Rain with wind past 20 mph. An umbrella would only flip inside out, so a rain jacket goes over the hoodie instead.
• Snow. The same rain jacket over the hoodie, and boots. One degree colder, the puffer sheds snow on its own and the rain jacket drops out.

On a wet day, pick the fleece over the hoodie. Polyester dries fast. A cotton hoodie that gets damp at 9am can still be damp at 5pm.

Same 40 degrees, two different people

The top Google results for this question include people from warm places asking what to pack for a cold trip. If that's you, expect 40°F to feel colder than it does to a local, at least for the first week. Why am I always cold explains why.

The app, though not this website, asks at setup whether you run hot or cold, and shifts the feels-like number 4 degrees either way. At 40°F both answers change the outfit:

• Runs cold, 4 degrees down. Effectively 36°F. Puffer jacket and beanie.
• Neutral. 40°F. Hoodie and vest, boots.
• Runs hot, 4 degrees up. Effectively 44°F. Hoodie and vest, with sneakers instead of boots.

The app also learns from your ratings, by up to 6 more degrees. At that limit the same 40°F forecast runs from a puffer with gloves to a long sleeve and a fleece.

Quick answers

How many layers should you wear in 40 degree weather?

Three on top. At a feels-like 40°F (4°C), Comfie's engine wants a long sleeve, a hoodie and a puffer vest, which adds up to 8 warmth points. One degree colder it's still three layers, but the vest becomes a puffer jacket and the target rises to 10. Plain jeans cover your legs.

What jacket should you wear in 40 degree weather?

Usually a puffer. A puffer vest is enough only when the air is still and dry, because a 3 mph breeze already makes 40°F feel like 38°F (3°C), which is puffer weather. Rain anywhere in the forecast swaps the vest for a light jacket with sleeves.

Is 40 degrees warm enough for shorts?

Not in Fahrenheit. At 40°F (4°C) you want jeans, and Comfie doesn't suggest shorts until a feels-like 80°F (27°C). In Celsius it's the other way around: 40°C is 104°F, which is shorts, tank top and sandals weather, plus a sun hat and sunscreen when the UV is high.

Is a hoodie enough for 40 degree weather?

Not on its own. A long sleeve and a hoodie add up to 6 warmth points, and a feels-like 40°F (4°C) asks for 8, so a puffer vest goes over the top. With any breeze the target rises to 10 and a puffer jacket replaces the vest. The hoodie can stay underneath.

How much colder does wind make 40 degrees?

On the US wind chill scale, 40°F feels like 36°F (2°C) at 5 mph, 34°F (1°C) at 10 mph and 30°F (-1°C) at 20 mph. The first few miles an hour cost the most. Even 3 mph takes off about two degrees, which is enough to change the outfit at 40°F.

Can you wear sneakers in 40 degree weather?

Comfie says boots. It keeps sneakers on down to a feels-like 42°F (6°C) and switches to boots below that. So sneakers are fine on a mild afternoon in the mid 40s, but at 40°F itself, or in snow at any temperature, wear boots.

So what do you wear today?

Three checks, in this order:

1. The feels-like number. From 40 to 47°F (4 to 8°C), a long sleeve, a hoodie and a puffer vest. At 39°F or colder, a puffer jacket and a beanie, plus gloves under 35°F.
2. The wind. Still air, trust the vest. Anything you can feel on your face, take the puffer.
3. The afternoon. 40°F at 8am can be 55°F by 2pm, which is hoodie-only weather, and you're carrying the vest. See cold morning, warm afternoon. For the neighboring temperatures, see what to wear in 50 degree weather and what to wear in 30 degree weather.

Still air at 40°F? Vest. Anything else? Coat.

Let Comfie do the checking

The live demo on the homepage runs these exact bands against real weather, wind included. Type your city and you'll see whether today is a vest day or a coat day, no download needed.

The iPhone app goes further. It learns whether you run hot or cold, so a still 40°F morning can put you in the puffer if that's what you actually need. Free to download, no ads.

Where these numbers come from: Comfie's own outfit engine, the same code behind the app and the demo on this site. The wind table and chart feed the National Weather Service wind chill at 40°F air into that engine. The demo's weather comes from Open-Meteo. Temperatures are feels-like unless stated, and Celsius is rounded to the nearest degree.