Awning Wind, Sun and Rain Sensors: How They Work, Where to Mount Them, and How to Calibrate
Quick answer
Motorized awnings use two kinds of wind sensor: vibration (motion) sensors mounted on the front bar that retract the awning when it shakes, and anemometers mounted on the wall that measure wind speed. Vibration sensors are cheaper and react to the awning's actual movement; anemometers measure wind directly but must be placed where they see the same wind as the awning. Sun and rain sensors add automatic extension and retraction based on light and precipitation.
An awning wind sensor automatically retracts a motorized awning when wind threatens it. There are two main types: a vibration or motion sensor, a small battery-powered unit clipped to the front bar that detects shaking, and an anemometer, a wall-mounted spinning cup sensor that measures wind speed. Sun sensors extend or retract the awning based on light intensity, and rain sensors retract it when precipitation starts. A sensor typically costs $100 to $400 and is the most effective single upgrade for protecting an awning that is ever left out unattended.
This guide covers the sensors themselves. If you are still deciding on a motor, see our motorized awnings guide and our guide to awning motors.
Vibration sensors vs anemometers
| Factor | Vibration (motion) sensor | Anemometer (cup wind sensor) |
|---|---|---|
| What it measures | Movement of the front bar | Wind speed at the sensor location |
| Mounting | Inside or on the front bar | Wall, fascia or post near the awning |
| Power | Usually battery, wireless | Often wired, some solar or battery wireless |
| Strength | Responds to what actually threatens the awning; no siting problem | Can act before the awning starts moving; works for multiple awnings |
| Weakness | Only works when extended; can miss steady wind that loads fabric without shaking it | Wrong placement gives misleading readings; moving parts wear |
| Best for | Single lateral-arm awnings, most homes | Exposed sites, multiple awnings, commercial installs |
Many installers fit a vibration sensor on residential lateral-arm awnings because it measures the thing you care about, which is how hard the awning is being pushed around. Anemometers suit storefronts and properties with several awnings, where one wall sensor can protect them all, and sites where you want the awning retracted before gusts hit, for instance on a hilltop or near open water.
How vibration sensors work
A vibration sensor contains an accelerometer. When the front bar moves beyond a set threshold for long enough, it sends a retract command to the motor by radio. Most have a dial or button-based sensitivity setting with several steps. Key behaviors:
- Lockout after trigger. After a wind retraction, most systems block extension commands for a period (often several minutes) so someone cannot immediately re-extend into the gust.
- Priority. A wind retract usually overrides remotes, schedules and sun sensor commands.
- Battery status. Many sensors send a periodic signal; some motors will retract or refuse to extend if they stop hearing from the sensor. Not all do, so a dead battery can leave you unprotected. Replace batteries annually, or when the low battery indicator appears.
How anemometers work
The anemometer's cups spin faster as wind increases, and its controller compares speed to a threshold you set, usually in mph, km/h or a numbered scale. Most retractable fabric awnings should be retracted in sustained winds of roughly 20 to 25 mph or gusts approaching that, but the right setting depends on your awning's rating and the sensor's position. Awnings tested under the European standard EN 13561 are assigned wind resistance classes 0 to 3, with higher classes tested to higher wind loads; see our awning wind ratings guide for how to interpret them.
Threshold is not the same as rating: The wind the anemometer sees is rarely the wind the awning sees. A sensor in the lee of a wall reads low; one on a corner reads high. Set the threshold conservatively and adjust after observing real conditions.
Sun sensors
A sun sensor measures light intensity (lux). When light stays above a threshold for a delay period, it extends the awning; when light stays below for a delay, it retracts. Delays, often several minutes, stop the awning cycling every time a cloud passes.
Sun sensors are most useful when protecting a room from solar heat gain while nobody is home. According to the U.S. Department of Energy's Energy Saver guidance, awnings can reduce summer solar heat gain by up to 65% on south-facing windows and up to 77% on west-facing windows. A sun sensor helps capture that benefit without someone being there to press the button. Our awning energy savings guide covers the numbers in more detail.
Many sun sensors are combined with a wind function in one unit, and some include a temperature input that prevents extension in freezing conditions.
Rain sensors
Rain sensors detect water on a sensing surface and send a retract command. Use them on awnings that must not hold water: low-pitch awnings, wide spans, and awnings over furniture you would rather get wet than risk bent arms. A retractable awning is a shade device; even a well-pitched one can pond water in heavy rain. If the awning retracts wet, extend it to dry within a day or two to avoid mildew (see awning mold and mildew).
Some homeowners prefer the opposite behavior: keeping a steeply pitched awning out in light rain to cover a patio. That is reasonable only if the awning is pitched for drainage (at least about 14 degrees, or about 3 inches of drop per foot of projection) and the rain is light. A rain sensor removes that choice, so decide which behavior you want before buying one.
Where to mount each sensor
- Vibration sensor: on or in the front bar, near the center of the span where movement is greatest, or as the maker specifies. Mount it level and in the orientation shown in the instructions.
- Anemometer: where it sees the same wind as the awning: typically on the wall near the awning, at or slightly above the awning's height, clear of corners, eaves and chimneys that create turbulence or shelter. Never mount it under the awning.
- Sun sensor: where it sees the sun that hits the area you want shaded, and never in the awning's own shadow. If it sits under the extended fabric it will read shade and retract, then read sun and extend, repeatedly.
- Rain sensor: exposed to open sky, not under eaves or the awning, and angled so water drains off the sensing surface.
- All sensors: within radio range of the motor. Masonry walls and metal cassettes reduce range; test before final mounting.
Calibrating thresholds
- Start sensitive. Set the wind threshold toward the more sensitive end. A few unnecessary retractions cost nothing; a missed gust can cost the arms.
- Test the trigger. For a vibration sensor, tap or shake the front bar with the awning extended and confirm it retracts. For an anemometer, spin the cups by hand or use the maker's test mode.
- Observe for two weeks. Note when it retracts. If it retracts in light breezes that leave the awning steady, reduce sensitivity by one step.
- Set sun thresholds on a clear day. Choose a light level that matches the moment you would want shade, and set delays long enough to ignore passing clouds.
- Retest seasonally. Sensor positions and nearby vegetation change; recheck each spring along with routine awning cleaning.
Worked example
A west-facing patio awning in a suburb is protected by an anemometer set to 20 mph, mounted on a fascia that is partly sheltered by the neighboring garage. The owner notices the awning shaking noticeably on gusty afternoons without retracting. Suppose the shelter makes the sensor read about 25% low, so it sees 75% of the actual wind. Then a 20 mph setting only triggers at about 20 / 0.75 = 27 mph of real wind, above the 20 to 25 mph guidance. Two fixes: lower the threshold to about 15 mph (15 / 0.75 = 20 mph actual), or move the sensor to an unsheltered spot. Moving it is better because the shelter effect varies with wind direction.
What sensors cannot do
Sensors reduce risk but do not make an awning storm-proof:
- A sudden strong gust can arrive faster than a wide awning can retract, which may take a minute or more.
- If power is out, the sensor cannot retract the awning unless the motor has battery backup.
- A vibration sensor does nothing while the awning is retracted, so it cannot protect against an awning being extended into an approaching storm by a schedule. Build safety rules into automations, as described in smart home awning control.
- Snow and ice: sensors do not detect them. Retract before snow and follow winterizing guidance.
If sensors stop triggering, check batteries and pairing first, then the steps in our motorized awning troubleshooting guide.
Who needs which sensor
- Anyone who leaves the awning out unattended: a wind sensor of some kind.
- Exposed, coastal or hilltop sites: anemometer, or both types.
- West or south-facing rooms that overheat: sun sensor.
- Low-pitch or very wide awnings in rainy climates: rain sensor.
- Small window awnings in sheltered spots, used only while home: sensors are optional.
To price sensors into a full project, use the awning cost calculator.
Frequently asked questions
What wind speed should an awning sensor be set to?
Most retractable fabric awnings should be retracted in sustained winds of roughly 20 to 25 mph or gusts approaching that, but follow the awning manufacturer's rating. Because a wall-mounted anemometer may read lower or higher than the wind at the awning, many installers set a lower threshold and adjust after watching how the awning behaves. Vibration sensors are set by sensitivity level rather than speed.
Do vibration sensors work with any motorized awning?
Only with motors that use the same radio protocol. A sensor designed for one system will not talk to a motor on another. Check the motor's brand and protocol, then buy a sensor listed as compatible. Wired motors need a separate control box to accept sensor inputs. Some awnings ship with a sensor pre-paired, which simplifies setup.
Why does my awning keep extending and retracting on its own?
The usual cause is a sun sensor sitting in the awning's own shadow. When the awning extends, the sensor reads shade and retracts it; then it reads sun and extends again. Move the sensor to a spot the fabric never shades, and lengthen the sun delay so passing clouds do not trigger cycles. Overly sensitive wind settings can cause similar retractions.
How long do awning sensor batteries last?
Battery life varies with the model, how often the sensor transmits and climate. Replacing batteries once a year, before the season starts, is a simple habit that avoids a sensor failing silently. Cold weather shortens battery life. If the sensor or remote has a low-battery indicator, act on it promptly rather than waiting for the sensor to stop working.
Sources and further reading
- U.S. Department of Energy, Energy Saver: Energy Efficient Window Attachments
- European Committee for Standardization, EN 13561: External blinds and awnings, performance requirements including safety
- Somfy: installation guides for wind, sun and motion sensors
- National Weather Service: Beaufort wind scale and wind terminology
How we write our guides: figures are typical US ranges checked against manufacturer documentation, published standards and installer pricing. Read our editorial standards. Spotted an error or outdated detail? Request a correction.