Everyday, Hot, and Cold Weather Clothes

I tend to set their winter clothes to sweaters and slacks/jeans with shoes suitable for inside with only one or two set as actual heavy winter wear, so it's not as jarring when they're wearing winter clothing indoors.

How much they change also depends on where your sims live. Some worlds get colder/warmer than others.

Also if you have a thermostat in your sims house it helps because they'll wear everyday after taking their showers/baths if the thermostat is set to counter whatever the temperature is.