Most of the Year's Rain Comes in Three Months
Redding's rain doesn't spread itself out. Going by NOAA's climate normals for the Redding airport, the city averages 33.52 inches of precipitation a year, and the three wettest months are December (6.31 inches), January (6.04 inches) and February (5.48 inches). Together that's more than half the year's total in a quarter of the year.
So a long, dry summer turns into a few months of steady and sometimes heavy rain, and a lot of cars go straight from one to the other without anything being checked: wiper rubber that baked all summer, a cabin air filter full of dust, tires that wore down over a season of hot pavement, and a defroster nobody has used since last winter.
This post is about everyday rain driving around town. For trips up I-5, 299 or 44, see winter car prep for the mountain routes.
Windows That Fog Up and Won't Clear
Fog on the inside of the glass is moisture from the cabin, from wet jackets, damp floor mats and everyone's breath, condensing on a windshield that's colder than the air inside. Clearing it is about drying that air, not just warming it.
The setup that works on most vehicles:
- Select defrost. On most vehicles, defrost mode also runs the A/C compressor, even with the temperature set to hot. The A/C is what pulls moisture out of the air.
- Turn the temperature up. Warm air holds more moisture and warms the glass.
- Use fresh air, not recirculate. Recirculating keeps the humid air you're trying to get rid of.
- Clean the inside of the glass. A film on the inside of the windshield gives fog something to cling to, and it smears into glare at night.
If you do all of that and the glass still won't clear, the car is telling you something:
- The A/C isn't working. A compressor that doesn't engage means defrost is just blowing warm, wet air at the glass. A weak A/C often shows up as slow defrost in winter before anyone notices it on a hot day. See A/C repair.
- The heater is weak. Lukewarm air can't keep the glass warm. Our heater troubleshooting guide covers the usual causes.
- A greasy film and a sweet smell. That's coolant vapor from a leaking heater core, and it fogs the glass faster than the defroster can clear it. See heater repair.
- Weak airflow at every fan speed. Often a cabin air filter packed with a summer's worth of dust, sometimes a blower problem. A wet, dirty filter can also smell musty.
- Recirculate stuck on. If the air door that switches between fresh and recirculated air has failed, the cabin never gets fresh, drier air.
Damp Carpet Means Constant Fog
If the windows fog up every time you get in, check the floor. A car with water in the carpet is humid inside all the time, and no defroster wins that fight. The usual ways water gets in:
- Clogged cowl drains at the base of the windshield, where leaves and debris collect and rainwater backs up toward the cabin air intake.
- A clogged A/C evaporator drain, which sends condensation onto the passenger-side floor instead of under the car. That water is clear and has no smell; coolant from a heater core smells sweet and feels slightly greasy.
- Sunroof drains that are blocked or have come disconnected.
- Door and windshield seals, or the plastic moisture barrier behind a door panel that was removed and never sealed back up.
Finding it takes more than a look. A tech pulls back the carpet, because the padding underneath can be soaked while the top feels nearly dry, checks each drain, and water-tests the car with a hose while someone watches from inside. Then the carpet and padding have to actually dry out, or the fogging and the musty smell come right back.
Wipers and Washer Fluid
Wiper blades wear out from sun as much as from use, and after a Redding summer a lot of them are hardened and cracked before the first storm.
- Replace blades that streak, chatter, skip or leave unwiped arcs. Do it before the rains, not during the first one.
- Check the washer system. Nozzles clog and get knocked out of aim, and a washer pump can fail quietly over a dry summer. You find out when the road spray hits.
- Fill the reservoir with washer fluid, not plain water, which doesn't cut road film the same way. If you'll be heading up the hill, use a winter-rated fluid that won't freeze.
Tread, Pressure and Hydroplaning
Hydroplaning happens when water builds up between the tire and the road faster than the tread can push it out of the way. The tire rides up on a film of water and the steering goes light. Worn tread, low pressure and speed all make it more likely, and standing water after a heavy rain is where it happens.
- Tread depth. Every tire has wear bars molded across the bottom of its grooves. When the tread is flush with them the tire is done, and wet grip drops off well before that. There's a quick coin test on our tire services page.
- Uneven wear. A tire worn down on its inside or outside edge can look fine from the front and still have little tread where it counts. That's usually an alignment problem, and it's worth fixing before new tires go on.
- Pressure. Underinflated tires don't clear water as well. Cold weather lowers pressure, about 1 PSI for every 10°F drop according to AAA, so tires that were right in late summer are often low by the rainy season. See why the tire pressure light comes on in cold weather.
If you do hydroplane, ease off the gas, don't brake hard, and keep the wheel pointed where you want to go until the tires grip again. Turn cruise control off in heavy rain so the car isn't holding speed for you.
Headlights: Seeing and Being Seen
Short days and dark, rainy commutes make lights matter more than they do the rest of the year.
- Cloudy, yellowed lenses cut a lot of light output. Restoring or replacing them makes a real difference on a wet night.
- Moisture inside a headlight that doesn't clear, like droplets or standing water inside the lens, usually means a cracked housing or a failed seal, and it can take out bulbs and the electronics inside the assembly.
- Aim. Headlights aimed too low light up very little road. Aimed too high, they glare into oncoming drivers' eyes, and wet pavement makes that worse.
- Every bulb. Brake lights, turn signals and the third brake light matter more when the driver behind you is looking through a wet windshield.
Turn your headlights on whenever your wipers are on. In rain, being seen matters as much as seeing.
What We Check Before the Rains
Ask us to look over the wiper blades and washer system, defrost performance and A/C compressor operation, heater output, the cabin air filter, the carpets and drains for water getting in, tread depth across each tire and pressure, and every exterior light. You'll get a written estimate before any repair, and the work is backed by our 12-month/12,000-mile warranty on parts and labor.
Windows fogging up or wipers smearing? Call (530) 785-9900. 5490 Churn Creek Rd, Redding, CA 96002. Mon–Fri 8AM–5PM.