Here's a strange one. Summer is hot, humid, and generally considered rough on fragrance longevity, yet a lot of people find their scent fading faster indoors in January than it did outside in July. That's not in your head, and it's not really about the season at all. It's about what's happening inside your house.
Central heating is quietly working against you
Indoor heating systems don't just warm the air, they strip moisture out of it. Relative humidity indoors during winter, with the heat running most of the day, can drop dramatically lower than outdoor humidity even on a cold, damp day. Your skin sits inside that dry air for hours at a time, and skin that's been dehydrated by dry indoor air behaves a lot like skin that's simply dry to begin with: it holds onto fragrance less, and lets it evaporate faster.
So the paradox isn't really a paradox. Outdoor winter air might be cold, but it's often more humid than the air inside your own living room once the heat's been running since 6am.
What this actually does to a fragrance
Fragrance needs some moisture on skin to bind to and release slowly over the day. Take that moisture away and the lighter top and heart notes burn off faster than they're supposed to, which is why a fragrance can smell like it's "gone" by early afternoon in winter, even though the same fragrance lasted well into the evening back in June. It's not weaker. The surface it's sitting on just isn't holding it the way it did a few months ago.
The fix is almost embarrassingly simple
Moisturize more in winter than you think you need to, and do it right before you apply fragrance, not hours earlier. An unscented body lotion or oil, applied while skin is still slightly damp, gives fragrance something to hold onto that dry, heated indoor air has otherwise taken away. If you're someone who runs a humidifier at home, you may already be inadvertently solving half this problem without realizing why your fragrance seems to last better on those days.
It's a small adjustment, but it's the difference between blaming a fragrance you actually love and just giving your skin what it needs to hold onto it a little longer.