It's raining. Actually it's pouring. Golf ball-sized rain droplets are pounding on your windshield. You flip on your wipers, which only make matters worse. As you bob your head, struggling to catch a glimpse of clarity through cloudy, streaked glass you will probably curse and think something like, ?OMG, what is wrong with me? Why didn't I replace these stupid things?!?

Guess what? Life doesn't have to be this hard. Most experts say you should replace your wiper blades every six to twelve months for optimum performance and driving visibility. That's because the materials don't last forever-- natural rubber deteriorates over time. Halogen-hardened rubber and synthetic rubber provide longer life, but eventually fall victim to environmental factors as well. Think about it. Your wipers are exposed to nature's elements 100% of the time. Exposure to sunlight and ozone will cause the rubber to age, even if you barely use your wipers.

The irony is you really only think about your wipers when you wished you had replaced them -- times when you vision is obscured by water, road splash, sleet or snow on the windshield. But good visibility requires wipers that are in good condition. If the wipers are chattering, streaking or otherwise failing to wipe cleanly and consistently, you need new blades -- Pronto!

But what really happens to wiper blades over time? As they age, they lose much of their flip-over flexibility thus losing their ability to wipe cleanly. They can develop a permanent set or curvature, which prevents full contact with the windshield. This is more likely to occur on vehicles that are parked outside in the hot sun all day. The sun bakes and hardens the rubber making them streak and chatter because they've taken a set and won't follow the curvature of the windshield. Not only are they dangerous, but annoying.

Cold weather can also affect your blades? life. Freezing temperatures make rubber hard and brittle, increasing the tendency to crack and split. For you snowy drivers, your wipers can become clogged with ice and snow, preventing the holder from distributing spring tension evenly over the blade. The blade then "freezes up" and leaves smudges as it skims across the glass. Driving in the snow is hard enough.

Heavy use can take a toll on your wiper blades, too. Dust, abrasives, road grime and even bug juice wear away the edge that allows the blades to wipe cleanly. As blades lose their edge, water gets under the blade and remains on the glass. The result is reduced visibility and poor wiping action.

If your blades are chattering, streaking or doing a lousy job of wiping, it is time for a replacement. Blades are cheap and easy to replace.

You should also check your windshield washer system. Do both squirters work? A nozzle could be clogged with dirt or a hose may be kinked or loose. Do the nozzles need adjusting? Does the washer pump deliver an adequate stream of solvent? The vehicle may have a weak washer pump, or a clogged, kinked or loose hose.

The wiper blade performance depends on the condition of the wiper arms and holders. The amount of spring tension on the wiper arm, the number of pressure points or claws that hold the blade, and the design of the blade itself all affect the blade's wiping ability. If the springs in the arms are worn out, the wipers may not be pressing firmly enough to wipe your windshield clean. In this case, replacing the blades won't make any difference because the problem is weak arms not bad blades.