Wind and noise: Santa Ana winds, sea breeze and still nights
Updated
Modeled estimates for general information only — not measurements, not a guarantee, and not for legal, medical or real-estate decisions.
Wind and still air change how far road noise carries, mostly in the evening and at night. On the Quiet LA map, a Wind switch in the layers panel shows road noise on a still, clear night, in a breeze, in an evening sea breeze or on a Santa Ana night. They are typical patterns, not forecasts.
Open the map on a still, clear night
How wind and still air change how far noise carries
Sound bends with the air it travels through. On a still, clear night sound tends to bend back down toward the ground, so it carries farther. When a breeze mixes the air, that bending weakens and less sound reaches distant places. With a wind, the side downwind of a road hears more of it and the upwind side less.
The main map assumes typical Los Angeles weather, with sound carrying farther in the evening and at night than in the day. Close to a road, the weather changes little. The differences between the weather views and the typical map are small, usually a few dB, which is within the error at a single address.
What the Wind choices on the map do
The Wind switch works in two periods, Evening and Night, and in the Field and Bands displays. Switch it on and pick a choice:
- Still (Night). The night level with sound bending back toward the ground on every path, the case where sound carries farthest.
- Breezy (Night). The night level with mixed air that does not bend sound toward the ground. The typical night lies between Breezy and Still, close to the Still end.
- Sea breeze (Evening). The evening sea breeze from the coast.
- Santa Ana (Night). The dry offshore wind of a Santa Ana night.
Sea breeze and Santa Ana are an approximation from wind direction, not a separate propagation run. For each place the model compares the direction of the nearby roads with typical wind directions in hourly airport weather records (LAX, Burbank, Long Beach and Palmdale, 2020 to 2024), so the downwind side of a road gets more of its sound and the upwind side less.
What the weather views leave out
- Forecasts and today’s weather. Every view is a typical pattern.
- Canyon and pass winds. Airport records miss them, and roads running in different directions average out.
- Checks against measurements in wind. The views have not been checked against measurements taken in wind.
- Anything but road noise. The weather views show road noise only; trains, aircraft and sirens are not added.
- Day and 24 h. There is no weather choice for them.
See Limits, How it’s made and Sources & methods. For how roads themselves are modeled, see freeway and road noise.
Open this on the map
Each link opens the map in the Night or Evening view with the weather choice already on. Switch between them in the layers panel and compare the colors along the freeways. Select a building at street zoom and the place panel gives the night range between breezy and still air.
- Night, still and clear (sound carries farthest)
- Night, breezy (mixed air)
- Night, Santa Ana
- Evening, sea breeze
- Night, typical weather (the main map, for comparison)
Common questions
How do Santa Ana winds affect noise?
In the model, a Santa Ana night changes which side of a road gets more of its sound, depending on how the road runs against the typical wind direction. It is an approximation from wind direction, not a separate propagation run, and the change from the typical map is usually a few dB.
Why does noise carry farther at night?
On a still, clear night sound tends to bend back toward the ground, so it carries farther. The map assumes sound carries farther in the evening and at night than in the day, and its Still view shows the case where it carries farthest.
Does the sea breeze change freeway noise?
It depends on which side of a road a place is on and how the road runs against the breeze: the downwind side hears more and the upwind side less. The map’s Sea breeze view shows this for the evening, as typical patterns and not a forecast.
Is the wind view a forecast?
No. Every weather view is a typical pattern. It does not show today’s weather and has not been checked against measurements in wind.
Sources
- Iowa Environmental Mesonet: ASOS hourly observations NOAA/NWS airport weather records (public domain) behind the typical wind directions.
- Caltrans: Technical Noise Supplement to the Traffic Noise Analysis Protocol (September 2013) General acoustics: how distance, the ground and weather change what reaches a listener.
- EUR-Lex: Directive (EU) 2015/996 The CNOSSOS-EU methods the model follows, including favourable and homogeneous propagation conditions.