Covering your teak furniture is generally not necessary. Premium teak wood can withstand most environments. Additionally, plastic covers that do not breathe can actually make matters worse. They can trap moisture underneath, creating an environment for mold and mildew to thrive.If you are going to be away for extended periods of time and just feel better covering the teak furniture, buy your covers a little big and use inflatable pillows or toys to create some space, or dome effect, so air can circulate.One exception may be in locations that get a lot of snow. If many inches of snow sit on the furniture for extended periods of time, the temperature and moisture may negatively affect the wood. Also, when the snow melts, it will be a lot of water on the table and make take exceptionally long to dry. The occasional snow is probably ok, but if you’re reading this in Buffalo, NY, you may consider covering your furniture in winter.