You step outside on a chilly winter morning, and something feels different. The air is crisp, biting, and yet smells unmistakably fresh. There’s a unique smell that’s hard to describe but instantly is somehow recognizable. What causes this distinct winter scent, and why is it so different from the way spring or summer smells?

Turns out, this effect is a mixture of thermodynamics and noses getting desensitized by the cold.

Winter does have a distinct odor

The cold changes odors. Cold air holds fewer molecules than warm air, which directly affects how scents travel. In summer, warm air molecules are more energetic, spreading out and carrying smells farther. In winter, the colder, denser air restricts the movement of odor molecules, creating a sharper, cleaner aroma.

Temperature also slows down the evaporation of certain volatile compounds. Volatile compounds are responsible for many natural smells, such as the earthy scent of soil or the sweetness of flowers. In winter, with freezing temperatures, these compounds evaporate less readily. This means fewer smells are present in the air, particularly unpleasant odors like garbage, car exhaust, or heating oil.

But cold air doesn’t just limit smells; it enhances some. Winter’s dry, crisp air can make certain scents, like wood smoke from a fireplace, seem more intense because they are less diluted by moisture in the air.

Your nose changes with the seasons

When it’s cold outside, the olfactory receptors that lie deep inside the nose (onto which odor molecules attach causing an electrical signal to be sent to the brain which we process into smell) nestle themselves deeper in the nose, as a protective response against low temperatures that might hurt them. This makes it harder for odor molecules to cling and, consequently, affects your smell.

During colder months, people also tend to spend more time indoors, where heating systems can dry out nasal passages. This dryness can dull your olfactory receptors, making it harder to detect faint smells.

There’s also a psychological effect. If you’re more attuned to winter holidays, you may be quicker to pick up on pleasant. Think of fresh pine from Christmas trees, sweet spices like cinnamon and clove in holiday baking, or the citrusy tang of oranges often associated with the season. These smells, though not exclusive to winter, feel heightened by their cultural and emotional significance.

So, the next time you step outside on a frosty morning (or afternoon), take a moment to breathe deeply. What you’re smelling is a complex interplay of cold air, olfactory changes, and your own heightened awareness. It’s winter’s way of reminding you to savor the season, one sniff at a time.