The WXT520, manufactured by Vaisala, is a solid-state, all-in-one weather instrument that measures wind speed and direction, precipitation, barometric pressure, temperature, and relative humidity. Its small size makes it ideal for quick, short-term deployments. However, the WXT520 is not intended for weather stations that require research-grade performance.

Benefits and Features

  • Low maintenance—no moving parts significantly reduces maintenance cost and time
  • Compact and lightweight
  • Low power consumption
  • Fast and simple to install
  • Outputs an SDI-12 signal that can be measured by many of our dataloggers
  • Combines the six most essential weather parameters in one instrument

Detailed Description

The WXT520's wind sensor consists of three equally spaced transducers that produce ultrasonic signals. Wind speed and direction are determined by measuring the time it takes for the ultrasonic signal of one transducer to travel to the other transducers.

Precipitation is measured one raindrop at a time. Whenever a raindrop hits the precipitation sensor, an electrical signal is produced that is proportional to the volume of the drop.

The WXT520 has a PTU module that contains a capacitive silicon BAROCAP® sensor for barometric pressure measurements, a capacitive ceramic THERMOCAP® sensor for air temperature measurements, and a capacitive thin film polymer HUMICAP® sensor for relative humidity measurements. The PTU is housed in a naturally-aspirated radiation shield that protects it and reflects solar radiation.


  • Electromagnectic Compatibility: Complies with EMC standard EN61326-1
  • IEC Standards: IEC 60945/61000-4-4, IEC 60945/61000-4-2
  • Input Voltage: 5 to 30 Vdc (below 5.3 V the measurement performance for high wind speeds may be degraded)
  • Typical Current Drain @ 12 Vdc: 0.1 mA (SDI-12 standby); 3 mA (Default Measuring Intervals)
  • Output: SDI-12
  • Operating Temperature: -52° to +60°C
  • Storage Temperature: -60° to +70°C
  • Operating Relative Humidity:
    0 to 100% RH
  • Height: 23.8 cm (9.38 in)
  • Diameter: 11.5 cm (4.52 in)
  • Weight: 650 g (1.43 lb)

Air Temperature

  • Measurement Range: -52° to +60°C
  • Accuracy: ±0.3°C @ +20°C
  • Output Resolution: 0.1°C

Barometric Pressure

  • Measurement Range: 600 to 1100 hPa
  • Accuracy:
    ±0.5 hPa @ 0° to 30°C;
    ±1 hPa @ -52° to +60°C
  • Output Resolution: 0.1 hPa

Relative Humidity

  • Measurement Range: 0 to
    100% RH
  • Accuracy:
    ±3% RH @ 0 to 90% RH;
    ±5% RH @ 90 to 100% RH
  • Output Resolution: 0.1% RH

Wind Speed

  • Measurement Range: 0 to 60 m s-1
  • Response Time: 0.25 s
  • Accuracy:  ±0.3 m s-1 or
    ±3% whichever is greater
    (0 to 35 m s-1); 
    ±5% (36 to 60 m s-1)

    Wind Direction

    • Measurement Range: 0° to 360°
    • Response Time: 0.25 s
    • Accuracy: ±3°
    • Output Resolution: 1°


    • Rainfall Measurement: Cumulative accumulation after latest automatic or manual reset
    • Collecting Area: 60 cm2
    • Output Resolution: 0.01 mm (0.001 in)
    • Field Accuracy for Daily Accumulation: Better than 5% (weather dependent; does not include possible wind induced error)
    • Rain Duration: Counting each 10-s increment whenever droplet detected
    • Rain Intensity: 1-min. running average in 10-s steps
    • Rain Intensity Range:
      0 to 200 mm hr-1 (broader range possible with reduced accuracy)



    The WXT520 is shipped with a mounting tube. The mounting tube fastens to a CM202, CM204, or CM206 crossarm via the CM220 Right Angle Mounting Bracket or 17953 1-in x 1-in NU-RAIL Fitting.

    The 25299 is an optional mounting kit for the WXT520. It provides better water protection. When using the 25299, the WXT520’s IP classification is IP66; otherwise its classification is IP65. The 25299 fastens to a crossarm via the CM220 bracket or 17953 NU-RAIL fitting.

    Datalogger Considerations

    Compatible Contemporary Dataloggers

    CR200(X) Series CR800/CR850 CR1000 CR3000 CR6 CR7X CR9000X

    Compatible Retired Dataloggers

    CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000

    Bird Spike Kit

    The 25300 Bird Spike Kit is used to discourage birds from roosting on the WXT520. This kit is fastened on top of the WXT520. It consists of a metallic band with spikes pointing upward. The spike’s shape and location ensure minimal interference of wind and rain measurements. The spikes are designed not to hurt the birds. Please note that when the kit is attached to the WXT520, more snow can accumulate on the WXT520, and the snow may melt slower.

    Frequently Asked Questions

    Number of FAQs related to WXT520: 5

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    1. The unit needs to be sent to Vaisala for repair.

    2. The example programs use a scan rate of 5 seconds to coincide with the internal update rate of 5 seconds. This update interval is preconfigured at Campbell Scientific for air temperature, relative humidity, and barometric pressure measurements.

    3. Campbell Scientific only supports using the WXT520 configured to our factory default settings. Other settings may produce data values that are different than the ones assumed in the provided example programs.

    4. The information included on a calibration sheet differs with each sensor. For some sensors, the sheet contains coefficients necessary to program a datalogger. For other sensors, the calibration sheet is a pass/fail report.

    5. This depends on the information contained in the calibration sheet:

      • If the calibration sheet contains coefficient information, Campbell Scientific keeps a copy, and a replacement copy can be requested.
      • If the calibration sheet does not contain coefficients, Campbell Scientific does not keep a copy. It may be possible to contact the original manufacturer for a replacement copy.