Santa Ana Winds, Dust, Windows and Solar Panels

Short answer: Santa Ana winds blow mostly from October through February. The winds are strongest in Southern California through and below the passes and canyons. They lift dust, soil and ash and drop it on glass and solar panels. The best time to clean is after the windy season (March or April) and again just before it starts (September or early October), plus after any big wind or smoke day.

What Santa Ana winds are

Santa Ana winds are a strong, warm and very dry wind blowing out of the bottom of mountain passes into the valleys and coastal plain, per Wikipedia.

The NOAA climate summary for the San Diego area is the closest NOAA document we could open. It says Santa Ana winds commonly occur between October and February, with December having the highest frequency of events, and that summer events are rare.

Cal OES says the seasonal winds typically blow in from October to December.

Relative humidities of less than 5 percent have been recorded in such events.

We use "fall through winter, most often October to February" as a working rule.

The winds matter to window cleaning for a simple reason: they are dry, strong and long. They lift fine dust and soil from dry ground, burn scars and construction sites. The South Coast Air Quality Management District said this in December 2023, and the dust advisory it issued is covered below.

Gusty Santa Ana winds can lift dust and soil into the air.

In November 2024, a red flag warning listed National Weather Service wind gusts for the Inland Empire.

Most gusts of wind were forecast to reach speeds between 15 and 25 miles per hour.

According to the National Weather Service, some gusts could reach between 35 and 45 miles per hour, with the highest levels possibly reaching 55 miles per hour.

A windblown dust advisory was issued by the South Coast Air Quality Management District for most of the Inland Empire.

In March 2026, the weather service issued another wind advisory for the area.

Which cities feel it most

Winds are strongest where air is funneled through a gap. Sources we could cite point to these places:

Fontana and Rialto, near the Cajon Pass. Wikipedia says Fontana is frequently affected by the strong, hot and dry Santa Ana winds as they blow through the nearby Cajon Pass. See Fontana and Rialto.
Alta Loma, below the canyons at the north edge of Rancho Cucamonga. The Alta Loma area experiences high winds known in the Inland Empire and the rest of Southern California as Santa Ana winds. See Alta Loma.
Etiwanda. Alta Loma and Etiwanda were most affected by the October 2003 Grand Prix Fire. See Etiwanda.
Corona. Wikipedia says autumn can be windy, with Santa Ana winds blowing in two or three times a year from October to December. See Corona.
Claremont, in the foothills. Gusty fall winds can bring fire danger to nearby foothill areas of Claremont. See Claremont.
Glendora, in the foothills. Santa Ana winds in the fall increase the risk of wildfires in the mountains around Glendora. See Glendora.
Ontario. Wikipedia says the winds hit the area frequently in autumn and winter. See Ontario.
Pomona. Wikipedia says seasonal Santa Ana winds arrive from the northeast in the fall. See Pomona.

We found no city-by-city measurements of dust on glass, so we do not rank the cities by how dirty they get. What the sources support is the exposure.

What the wind leaves behind

Dust and soil. Fine particles stick to glass and panels. On a dry window they brush off in places and smear in others.
Ash. After a wildfire or brush fire, ash lands the same way. It is gritty. Dry-wiping can scratch glass, so rinse first.
A muddy film after light rain. Light rain on a dusty window does not always rinse it clear. How much rain it takes depends on how much dirt there is.
On solar panels, lower output. Researchers have measured soiling losses that grow during dry weather. See the solar panel cleaning guide.

The Inland Empire cleaning calendar

Two things combine here: the windy season and a long dry season. One modeled weather data set for Ontario, built from NASA data and summarized by WeatherSpark, shows no rain from about April 22 to October 20, with February the wettest month. Ontario has a rainless period lasting about 5.9 months. So glass is dry-dusty for half the year and wind-dusty for the other half.

When	Why	What to do
March or April	Windy season is ending; the long dry spell starts in late April	Clean windows and panels so the dry months start clean.
Summer (optional)	Months with almost no rain; sprinklers wet the glass every day	A mid-summer visit if you are near a freeway, warehouse or trees, or your panel output is slipping.
September or early October	Just before Santa Ana season	Clear the summer film so wind dust lands on clean glass.
After any wind or smoke day	Ash and dust land at once	Rinse with water before you wipe. Book a visit if the glass has a gray haze.

A plan every 3 months (15% off each visit) lines up with these four points. Twice a year (8% off) covers the first and third.

What to do on a wind day

Close windows and doors. Wind-driven dust gets in through tracks and gaps, which is why screens and tracks are worth cleaning.
Do not wash windows or panels during the wind. The dust returns within hours.
After the wind drops, rinse with plain water before you wipe anything. Dry wiping grinds grit into the glass.
On solar panels, wait for cool hours and follow your panel maker's instructions. Do not go on a wet or dusty roof.
If you smell smoke or see ash, the same rule applies: rinse first.

What a cleaning costs

Outside windows are $9 each with a $130 minimum, and solar panels are $6 each with a $110 minimum, for single-story roofs, from the ground. Both together are 10 percent off. See the window cleaning cost guide for the full price list.

Common questions

When is Santa Ana wind season?

Mostly October through February. NOAA's San Diego climate summary says they commonly occur October to February, with December the most frequent month.

Should I clean my windows during Santa Ana winds?

No. Dust returns within hours. Wait until the wind drops, then rinse with water before wiping.

Does wildfire ash damage solar panels?

Ash is mostly a dirt problem that blocks some light. Rinse with water before wiping, because ash is gritty.

When is the best time to clean solar panels in the Inland Empire?

After the windy season in March or April, and again in September or early October before it starts.

Which Inland Empire cities get the strongest Santa Ana winds?

Sources point to places near canyon mouths and passes, such as Fontana, Rialto, Alta Loma and Etiwanda. We found no measurements that rank cities.

Where this applies

We work in every place within 15 miles of Ontario: Ontario, Upland, Montclair, Chino, Rancho Cucamonga, Claremont, Alta Loma, Eastvale, Pomona, Etiwanda, Chino Hills, Jurupa Valley, La Verne, Norco, Fontana, San Dimas, Diamond Bar, Corona, Walnut, Rialto, Covina, Glendora.

Related services: Window cleaning, Solar panel cleaning, Plans.

More guides

Sources

NOAA Technical Memorandum NWS WR-270, "Climate of San Diego" (Santa Ana winds commonly October to February; December most frequent; humidity under 5 percent). “Santa Ana winds commonly occur between October and February”
NOAA Technical Memorandum NWS WR-270, "Climate of San Diego" (Santa Ana winds commonly October to February; December most frequent; humidity under 5 percent). “are strongest through and below the passes and canyons”
Wikipedia, "Santa Ana winds" “a strong, warm, and very dry wind blowing out of the bottom of mountain passes into the valleys and coastal plain”
NOAA Technical Memorandum NWS WR-270, "Climate of San Diego" (Santa Ana winds commonly October to February; December most frequent; humidity under 5 percent). “Santa Ana winds commonly occur between October and February with December having the highest frequency of events. Summer events are rare.”
Cal OES, "Impending Santa Ana winds bring increased fire risk," October 14, 2023. “seasonal winds typically blow in from October to December”
NOAA Technical Memorandum NWS WR-270, "Climate of San Diego" (Santa Ana winds commonly October to February; December most frequent; humidity under 5 percent). “Relative humidities of less than 5 percent have been recorded”
South Coast AQMD news release, December 9, 2023 (gusts lift dust and soil; windblown dust advisory). “gusty Santa Ana winds, which can lift dust and soil into the air”
CBS Los Angeles, November 3, 2024 (red flag warning; gusts up to 55 mph; windblown dust advisory across the Inland Empire). “most gusts of wind reaching speeds between 15 and 25 miles per hour”
CBS Los Angeles, November 3, 2024 (red flag warning; gusts up to 55 mph; windblown dust advisory across the Inland Empire). “some gusts could reach between 35 and 45 miles per hour, with the highest levels possibly reaching 55 miles per hour, according to the national weather service”
CBS Los Angeles, November 3, 2024 (red flag warning; gusts up to 55 mph; windblown dust advisory across the Inland Empire). “a windblown dust advisory was issued by the south coast air quality management district for most of the inland empire”
KVCR News, "Wind advisory issued for Inland Empire," March 5, 2026. “The National Weather Service has issued a wind advisory for much of Southern California this week”
Wikipedia, "Fontana, California" (climate). “The city is frequently affected by the strong, hot and dry Santa Ana winds as they blow through the nearby Cajon Pass”
Wikipedia, "Alta Loma, Rancho Cucamonga, California" (winds; Grand Prix Fire). “The Alta Loma area experiences high winds known in the Inland Empire and the rest of Southern California as the 'Santa Ana winds.'”
Wikipedia, "Alta Loma, Rancho Cucamonga, California" (winds; Grand Prix Fire). “Alta Loma and Etiwanda were most affected by the October 2003 Grand Prix fire”
Wikipedia, "Corona, California" (climate). “can be windy due to the Santa Ana winds, blowing in two or three times a year from October to December”
Wikipedia, "Claremont, California" (climate). “Claremont can experience the gusty 'Santa Ana Winds', which can bring fire danger to nearby foothill areas”
Wikipedia, "Glendora, California" (climate). “warm Santa Ana winds in the fall increase the risk of wildfires in the surrounding mountains”
Wikipedia, "Ontario, California" (climate). “Santa Ana Winds hit the area frequently in autumn and winter”
Wikipedia, "Pomona, California" (climate). “seasonal Santa Ana winds originating from the northeast”

Written by Foothill Home Services. Local prices on this page are our own draft rates from the price list the quote tool uses. Where we quote an outside page, the quote is linked in the sources above, and we last checked this page on October 13, 2026. Other outside figures are described as the source reports them.

Santa Ana winds and dust: when to clean windows and solar panels near Ontario