Short answer: Replace wiper blades at least once a year, sooner if they show signs of wear or performance problems.

When to replace — look for these signs

• Streaking or smearing across the windshield.
• Skipping or chattering (blade vibrates or leaves gaps).
• Squeaking or unusual noise during use.
• Splits, cracks, or missing chunks of rubber.
• Bent or damaged blade frame or loose attachment.
• Poor contact with the glass (water beads left behind).
• Fogging or reduced visibility in rain/snow.

Recommended schedule

• Every 6–12 months for most climates (replace nearer 6 months in hot or snowy climates).
• Replace before seasons with heavy precipitation (e.g., before winter and the rainy season).
• If you use de-icing fluids, run windshield washer often, or park in sun a lot, expect faster wear.

Quick checks you can do

• Run the washer and watch for streaks/gaps.
• Press the blade rubber lightly — if it’s hard, brittle or uneven, replace it.
• Inspect visually for cracks, tears, or warped metal.

Practical tips

• Keep a spare set at home; replacement takes 5–15 minutes.
• Buy blades sized to your vehicle (sizes can differ driver/passenger). Check vehicle manual or measure the current blade.
• Consider beam-style blades for better performance in winter/ice; conventional blades are usually cheaper.
• Clean blades and windshield occasionally with mild soap to extend life.
• Replace both blades at once for even performance (especially if one is old).

Cost and disposal

• Cost: typically $10–$40 per blade depending on type/brand; installation at many auto shops may be free or inexpensive.
• Dispose of old blades in household trash (metal and rubber), or check local recycling options.

Safety note

• Don’t delay replacement — good wipers are essential for safe driving in rain, snow, and at night.

If you want, tell me your car make/model/year and I can tell you the blade sizes and a short step-by-step for replacing them.