Short answer: if you want to get ahead of a wet winter, clean your solar panels and windows in October or November, then look at your roof and stucco in spring. Stay off wet roofs, and call us for a visit between storms. This guide is for the 2026-27 winter. Next year’s version will be a new page. Prefer a checklist? See our fall rain prep guide.
What are forecasters saying about this winter?
As of mid-September 2026, NOAA’s Climate Prediction Center expects a very strong El Niño this winter, in its ENSO discussion. Its seasonal outlook favors a wetter-than-normal winter across California, strongest near the coast from December through April. Both pages update, so check them for the current picture.
A forecast is a likelihood, not a promise. We don’t predict storms, and nobody can tell you when a particular one will hit your street. What we can do is help you get your house ready, so you aren’t scrambling when the weather turns.
What does rain do for solar panels, and what doesn’t it do?
Rain can rinse loose dust off tilted panels. That’s the good part. The rest is less tidy.
- Rain can leave a mineral film or streaks as it dries on the glass.
- Light rain can turn dust and ash into a paste instead of washing it away.
- Rain generally doesn’t remove bird droppings or sticky buildup.
So a wet winter doesn’t mean your panels clean themselves. Some arrays come out of a storm looking better and others look worse. It depends on the tilt, the trees around you and what’s sitting on the glass when the rain starts.
When should I clean my solar panels?
Before the rains. If dust and ash are already on the glass in early fall, the first light storm wets them into paste. Cleaning first gets you a clear start to the season.
We clean panels by hand with soft brushes and purified water, with no high-pressure washing on the glass. Customers tell us they see up to 32% more output after a cleaning, though results vary by system.
After the storms, take a look from the ground. A gray film, white streaks or a muddy edge along the bottom of the glass are signs of buildup. Then call us for a visit once things dry out.
Some safety basics:
- Never go on a wet roof or up a ladder during a storm.
- Don’t climb up yourself to rinse panels. Wet glass and wet roofs are slippery.
- Don’t spray panels with a pressure washer. Hard spray can damage them.
For more, see our solar panel cleaning page, our guide on how often to clean solar panels and our guide on solar panels and wildfire ash.
What should I look for on my roof?
A wet winter can spread algae and moss. Those growths feed on moisture, and shaded slopes and spots under trees stay damp the longest. You may not notice anything in January. Spring is a good time to look, from the ground, for dark streaks, green patches or thick moss along the edges.
We softwash roofs, tile and shingle, with low pressure and a cleaning solution. We don’t pressure wash them. We guarantee our moss and lichen removal. If it takes more than one visit, we keep coming back as many times as it takes. Details are on our roof cleaning page, and our guide to roof algae and black streaks explains what you’re seeing.
We clean roofs. We don’t repair them. If you notice a leak, cracked tile or lifted shingles, call a roofer.
What does rain do to windows and screens?
Rain on dusty glass is a common cause of hard water spots and film. The water carries dust down the pane, then dries and leaves a ring of minerals behind.
Clean glass and clear tracks make a difference. If your screens are torn or the frames are bent, it’s easier to deal with them before the weather turns. See our window cleaning page, our guide on hard water spots on windows and our screen repair page.
What about stucco and the rest of the exterior?
Damp walls grow mildew and algae, especially on shaded sides of the house and low on the wall where splash and sprinklers reach. Stucco is porous, so it holds moisture. A winter with more rain can leave dark or green patches that weren’t there last year.
We softwash house exteriors with low pressure and a cleaning solution. Our house washing page explains how it works, and our stucco and house washing guide covers what to look for.
Should I think about my gutters?
Yes. Packed gutters hold water against the roof edge, and a heavy rain finds every blocked downspout. We clean gutters ourselves, and you can read about it on our gutter cleaning page. Our sister company Gutter Spa Club has its own guide for this winter, the El Niño gutter prep guide.
Will a wet winter keep birds away from my panels?
No. Birds still look for dry, sheltered spots, and the space under panels is one of them. Nesting doesn’t pause for rain. If you’ve seen birds around your array, our bird proofing service uses humane mesh, spikes and netting to close those gaps.
What can I do myself?
Plenty of it is a walk around the house. None of it needs a ladder.
Look at the panels from the ground in the morning light. Scan the roof with binoculars for dark streaks. Check that sprinklers aren’t hitting the walls or the roof edge, since extra water on top of a wet winter keeps stucco damp. Run a hand along each window screen and note any tears. Take a few photos now, so you can compare in spring and see what changed.
What’s the timeline?
This is a general guide. Your own schedule may shift with your trees, your roof and the weather itself.
| When | What to do |
|---|---|
| October to November, before the rains | Clean solar panels and windows. Clear gutters. Check screens and tracks. Look for birds and nests under panels. |
| December to March, during the wet season | Stay off wet roofs. Check panels, gutters and glass from the ground after storms. Book a visit between storms if buildup shows. |
| April to May, after the rains | Look at the roof and stucco for algae, moss and mildew. Plan spring cleaning of panels and windows. Check for nesting. |
What’s on the checklist?
- Clean solar panels before the rainy season
- Clean windows and clear tracks and sills
- Check screens for tears and bent frames
- Clear gutters and downspouts
- Look at panels from the ground after each big storm
- Look at the roof and stucco in spring for dark streaks and green growth
- Check under the panels for birds and nests
- Keep everyone off wet roofs and ladders
What can we do about it?
We’re Licensed & Insured, and estimates are free. We clean panels and windows by hand with purified water, softwash roofs and house exteriors, clean gutters, repair screens and install bird proofing. All our work comes with a 100% satisfaction guarantee. If you’re not satisfied, we’ll come back and make it right at no additional cost.
Homes near open hillside, like those in Porter Ranch, Calabasas and Tujunga, tend to collect dust fast. Homes in Chatsworth, Valencia, Thousand Oaks and Simi Valley each have their own mix of trees, tile roofs and wind. If you’re not sure what you need, we’ll take a look.
Get your free estimate
Call (818) 913-1626 Monday through Saturday, 7am to 7pm, or check the cities we serve page and send us a request for your area.