I have a clothes dryer which has been working fine until now.?

Check the location of the dryer. Inside moisture is caused by a difference in the inside/outside temperatures. Is there plenty of ventilation around your appliances? Does the sun ever shine directly on it (through a window or otherwise)? Lastly, check the temperature control, to make sure it hasn't been moved to "Air Dry". If it is on air dry, the clothes make dry okay, but residual moisture can remain on the drum interior.

Boy, that's baffling! I'm guessing with the change in weather there are some condensation issues here. It may be that the dryer is warm during the day and at night, cold air is causing moisture to condense on the walls of the dryer. This doesn't happen unless I'm guessing there may be an issue with the vent or the tubing that leads to the outdoor vent. Give it a look and see if it's in place or there are any tears or rips in the tubing. Good luck.

It may be that because it vents to the outside and it has been colder, the cold air from outside and the warm air from inside are making condensation inside your dryer. The wind may be blowing just right so it is blowing cold air into the dryer which in turn would be warm from being inside and there you go, condensation.

Has someone used a water hose outside by the dryer vent?

Check to see if you have good air ventilation. Check to see if your heating element is turning on. It's one of those two things.