How do you know when to change your windshield wipers?

The guy at the Auto Zone told me that it needs to be changed about every 6 months to a year. It also depends on where you live. California has no rain, so it tends to dry out the blades. I hear cleaning it with alcohol helps too, in restoring it a little longer.How do you know when to change your windshield wipers?
When they are not cleaning, when they are dry, tear, low profile.How do you know when to change your windshield wipers?
When they start streaking the windshield.How do you know when to change your windshield wipers?
When it pulls away from the glass, streaks and doesn't really clean, change it. It is best usually to change them every three to four months depending upon use and ware. Exposure to harsh sunlight may also take the moisture out of them.How do you know when to change your windshield wipers?
HINT: Squeek! Squeek! or pieces of rubber flying off, or no rubber at all.How do you know when to change your windshield wipers?
When they start leaving streaks, or fail to adquately clear the windshield of water, when they start to fray, pit, feel hard or brittle and/or start to chatter and skip as they cross the windshield, it is time to replace them. They are inexpensive enough to replace them on a regular basis (like once a year) if you feel like they aren't doing a really good job. This is particularly true if you live in the snow and icy parts of the country, or you live where there are a lot of bugs (which increased usage demands and causes pitting of the rubber), or dry, dusty areas where you use the windshield washer fluid a lot.How do you know when to change your windshield wipers?
you know you should change them when while it's raining you hear that irratating squeky noise.How do you know when to change your windshield wipers?
When they're like mine, and the rubber falls off, making the most horrific noise you'll ever hear when it scrapes across the windshield.How do you know when to change your windshield wipers?
Change them when you change your oil...that's when I do mine...rather, when Walmart does it for me!