The answer to this will depend on what type of humidifier you’re using. Evaporative models can get quite hot, and you need to take care of where to put them. Warm mist models also have a heating element, but they should still be safe to touch. An ultrasonic humidifier, however, is going to remain completely cool to touch and is a great option for all year round. For the best humidifier for winter, that warmth can be seen as a positive, but it does mean that you have to be more mindful when it comes to children and pets.