If you can’t see where you’re going, there’s going to be trouble. Your vehicle’s windshield wipers need to be in good condition at all times if you’re to avoid accidents.
How do you know when it’s time to replace your windshield wipers? Generally, they should be replaced every six to twelve months, depending on how often you use them. The rubber blades on the wipers wear down over time—the more you use them, the faster they wear down.
The obvious example of knowing when to change your wipers would be this: your windshield is not getting cleaned properly, and you can’t see out of it when you need to. When the blades seem to be passing over parts you need cleaned, or “skipping” over certain areas of the windshield, it’s time to replace your windshield wipers.
Some things that affect the wipers include dirt, debris and wind lift. Bad weather can quickly damage your blades. Dust and air 
pollution also affect the blades, wearing away their edges over time. Every now and then, you should visibly inspect the rubber blades to see if they’re still looking good, or if they’re worn down so much that you can see it’s time to replace them.
When blades lose their edge, water gets under them and ends up remaining on the glass. Visibility lessens as the wipers aren’t doing the intended job.
If your windshield wipers are making strange noises that you’d describe as chattering or thumping, it’s time to replace them. And if the wipers are scratching your vehicle’s glass windshield, it’s definitely time to get new ones.
