I don’t know, but I asked Google AI and:

Wood floors can become more slippery in the winter due to the increased likelihood of moisture and dirt being tracked in from outside. Additionally, the air tends to be drier in winter, which can affect the finish and surface texture of the wood. 

 Thanks! It probably something to do with the relative humidity dropping because the heat is running more often. 

 I’d say the lower relative humidity in cooler weather could definitely have an effect on the friction coefficient on hard surface floors. That, and wearing wool socks instead of cotton. 

 yes. if its surface temperature is very much different to the ambient air temperature, when the humidity is high, it will condense on the surface 

 🎯 

 Temperature is one of the things that can have an effect on it. 
Humidity being another major factor.

A few other things are-
 What wood it is. 
 What it's finished with. And how often it is refinished, polished, waxed 
 What it's cleaned with.
 

 Just checking the basics here, but have you recently started wearing (thicker) socks because it’s got colder…? 

 I noticed it even first thing in the morning getting out of bed, no socks. My wife mentioned it too. It was colder for a couple of days at night and in the morning. Yesterday the heavy rain moved in and it warmed up a bit. Floor is not slippery today. 

 Very strange! I suspect your condensation theory is probably right.  

 🤷🏻‍♂️😆