What should you be careful about on extremely cold days when using windshield wipers?

• Using them at high speeds can freeze the fluid on the windshield
  Explanation:

  "On extremely cold days, be cautious about using windshield washer and wipers at high speeds. Even if the fluid contains antifreeze, high speed combined with extreme cold can freeze the solution on the windshield and totally obscure your vision."
• It’s safe to use them at any speed
• Only using the washer fluid without wipers
• Keeping the wipers off completely