Why are businesses slower during the winter months? After the holiday season?

Even though it all depends on the type of business (bars, restaurants, malls, shopping centers, etc) I’ve noticed that certain places tend to slow down when it gets cold outside, especially after the holiday season, which makes sense, but when it comes to restaurants, I’ve noticed that less people are out late at night during this time of the year.

Which makes me wonder how much the weather affects businesses?

Not just the weather, but the days are shorter. Happy hour doesn’t feel right if the sun has already gone down.

It seems that you pretty much answered your own question here, at least to an extent. I think that, after the excesses of the holiday season- excessive shopping, excessive spending, excessive eating and drinking, the post-holiday months are a period to take a little break from all of that.

On the other hand, fitness clubs on January 2 typically have people packed in like sweaty sardines.

I, for one, look forward to the post-holiday winter shopping slowdown and take advantage of it whenever I can. I think it’s a money thing. People overspend during the holidays and tighten their belts for the following month. Easter will be here soon enough.

And, as @dolphinboy notes, people may also be watching their budgets after the holidays.

well, an obvious reason may be that in deep winter conditions, why would anyone want to leave the house unless necessary?

Especially for seniors – in much of the country winter snow & icy sidewalks make it dangerous at times.
And seniors make up about 1/5th of the population, and growing.

This is why we have online shopping. Right?

I chalk it up to shopping/buying fatigue.

I have been at the same gym since October 2004. The January spike is tiny now compared to what it was 20 years ago.