- Published Aug 18, 2025
- Last Modified Aug 18, 2025
- 5 min
How to Measure Wind Speed and Direction
Find out how to measure wind speed and direction with different anemometers and learn the Beaufort Scale for safe and effective wind monitoring.
Reviewed by David Carmichael, Solution Engineer (August 2025)
This comprehensive guide explains how wind speed is measured using various types of anemometers, how to determine wind direction, and how to interpret wind speed units and safety thresholds. Whether for weather monitoring, industrial use, or design applications like aerodynamics, understanding wind speed measurement is key to managing environmental conditions and ensuring safety.
What Instrument Measures Wind Speed?
The primary instrument used to measure wind speed is the anemometers. From traditional mechanical designs to advanced electronic models, anemometers offer reliable and accurate wind speed measurements. Portable handheld anemometers provide quick, convenient readings on the go, while larger mounted devices are used in weather stations and industrial environments.
Monitoring wind speed is crucial because strong winds can be hazardous. Measuring wind speed can help predict weather changes, improve safety protocols, and optimize designs in areas such as automotive engineering, architecture, and renewable energy.
How to Measure Wind Speed Using an Anemometer
There are three main types of anemometers commonly used:
Vane Anemometers
These instruments are available as portable handheld units as well as in larger formats. They work by using the same principle as windmills where the wind's energy was harnessed by driving a milling rotor propelled by large wind vanes.
The vane anemometers have a small propellor-type rotor that rotates when faced in the direction of the oncoming wind. The rotor speed is monitored by the electronics in the unit and a measure of wind speed is displayed on a digital display.
Cup Anemometers
These are the most recognized anemometer and widely used in meteorology and environmental monitoring. They have several cups configured horizontally in a cross format which is mounted on a rotating center pole. The wind is caught in the recess of each cup which propels and rotates the center spindle. The wind speed is then measured by electronically monitoring the rotational speed of the shaft and then shown on a display.
Thermal Anemometers
Thermal anemometers are commonly used in industry such as in a wind tunnel when working with aerodynamics. They work by passing an electric current through a very thin wire. The wire heats up and the temperature is monitored by a temperature sensor or in some cases by monitoring the current flowing through the wire.
When you place the wire assembly in a moving flow of air the temperature of the wire will drop. This will increase the electrical current flowing through the wire as its resistance falls. The change in current is interpolated by the electronics in the device and a direct read-out of airflow velocity or wind speed is shown on the display.
How to Measure Wind Direction
We have all seen the quaint weathervanes mounted on the idealistic country cottage where there is a rotating pointer in the form of a cockerel with its beak pointing out the wind direction. The cockerel will align with the wind direction and the leading edge of the sail (the head), will catch less wind so will always face in the direction of the oncoming wind.
Modern anemometers that possess the ability to measure wind direction as well as wind speed work in a comparable manner to the weathervane. Wind speed direction is measured in the same way. There is a small wind vane mounted on a rotating stem. The usual method of detecting the position of the stem is by using a set of magnetic sensors that relay the information to the device's electronics. There is also an onboard electronic compass. The instrument will show you wind direction by interpreting the position of the rotating stem relative to the magnetic north.
How to Measure Wind Speed in Knots
Today's anemometers allow users to select preferred units such as knots (nautical miles per hour), miles per hour (mph), kilometers per hour (kph), and sometimes feet per minute. Measuring wind speed in knots is common in maritime, aviation, and meteorological contexts.
What Wind Speeds Are Dangerous?
Wind speed classification typically uses the Beaufort Wind Scale, which ranges from force 0 (calm) to force 12 (hurricane). Wind speeds above force 5 (fresh breeze and above) warrant caution, as the impact on structures and safety increases significantly.
Wind Force | Wind Speed (mph) | Description |
|---|---|---|
| Force 0 | Less than 1 | Calm |
| Force 2 | 1-3 | Light breeze |
| Force 3 | 8-12 | Gentle breeze |
| Force 4 | 13-16 | Moderate breeze |
| Force 5 | 19-24 | Fresh breeze |
| Force 6 | 25-31 | Strong breeze |
| Force 7 | 32-38 | Moderate gale |
| Force 8 | 39-46 | Fresh gale |
| Force 9 | 47-54 | Strong gale |
| Force 10 | 55-63 | Whole gale |
| Force 11 | 64-73 | Storm |
| Force 12 | Greater than 73 | Hurricane |
Caution should be exercised when venturing out at any wind speed above force 5. Building damage is highly likely at force 9 and above.
So what wind speed is a hurricane? A hurricane is classed as the strongest wind force category and starts at 73 mph. This is classified as force 12. Within the force 12 range are five further categorizations and increases in hurricane wind speed:
Wind Force & Hurricane Category | Wind Speed (mph) |
|---|---|
| Category 1 Hurricane (Force 12) | 74-95 |
| Category 2 Hurricane (Force 12) | 96-110 |
| Category 3 Hurricane (Force 12) | 111-129 |
| Category 4 Hurricane (Force 12) | 130-156 |
| Category 5 Hurricane (Force 12) | 156 or greater |
Major damage to buildings and structures can occur with those kinds of high wind speeds.
Summary
Measuring wind speed accurately is essential across many fields, from weather forecasting and environmental safety to engineering and sports. Using various types of anemometers like vane, cup, and thermal models allows precise assessment of wind velocity and direction. Understanding units of measurement and referencing the Beaufort Scale help interpret wind strength and potential hazards effectively. With modern instruments offering portability and integrated direction measurement, wind data is more accessible than ever, empowering users to make informed decisions for safety, design, and performance.
