HC2-S3-L Temperature and Relative Humidity Probe
Accurate and Rugged
Superior performance and reliability
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The HC2-S3-L, manufactured by Rotronic, is a rugged, accurate temperature and humidity probe that is ideal for long-term, unattended applications. The probe uses an advanced capacitive sensor to measure relative humidity. The probe includes a filter to protect the sensor from dust and particles, for superior performance and reliability.

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Benefits and Features

  • Well-suited for long-term, unattended applications
  • Accurate and rugged
  • Compatible with most Campbell Scientific dataloggers

This product is available for repair and calibration



  • Electronics Operating Limits: -40° to +100°C
  • Storage Temperature: -50° to +100°C
  • Diameter: 15 mm (0.6 in)
  • Length w/o connector: 85 mm (3.3 in)
  • Length w/connector: 183 mm (7.25 in)
  • Weight: 10 g (0.35 oz)
  • Filter: Polyethylene (standard) or Teflon (optional, ordered separately)
  • Current Consumption:
    < 4.3 mA @ 5 Vdc
    < 2.0 mA @ 12 Vdc
  • Supply Voltage: 5 to 24 Vdc
  • Startup Time: 1.5 s typicala
  • Maximum Startup Current:
    < 50 mA for 2 μs
  • Analog Outputs
    Offset at 0 V: ±3 mV (maximum)
    Deviation for Digital Signal:
    < ±1 mV (0.1°C, 0.1% R. H.)

Air Temperature

  • Temperature Sensor: PT100 RTD, IEC 751 1/3 Class B
  • Measurement Range: -40° to +60°C (default)b
  • Output Signal Range: 0 to 1 V
  • Accuracy at 23°C: ±0.1°C with standard configuration settings
  • Long Term Stability: < 0.1°C/year
  • Sensor Time Constant
    [63% step change (1 m/s air flow at sensor)]
    Standard PE Filter: ≤ 22 s
    Optional Teflon Filter: ≤ 30 s [Typical 4 s, 63% of a step change (1 m/s air flow at sensor)]
  • Temperature Accuracy: see graph in manual

Relative Humidity

  • Sensor: ROTRONIC® Hygromer IN-1
  • Measurement Range: 0 to 100% RH, non-condensing
  • Output Signal Range: 0 to 1 Vdc
  • Long-Term Stability: < 1% RH per year
  • Accuracy at 23°C: ±0.8% RH with standard configuration settings
  • Sensor Time Constant
    [63% of a 35 to 80% RH step change (1 m/s air flow at sensor)]
    Standard PE Filter: ≤ 22 s
    Optional Teflon Filter: ≤ 30 s [Typical 10 s, 63% of a 35 to 80% RH step change (1 m/s air flow at sensor)]
  • RH Accuracy over Temperature: see graph in manual

a - The startup time is Rotronics specification. For programming, Campbell Scientific recommends a 2 s delay at 60°C, 3 s delay at 0°C, and 4 s delay at -40°C.

b - Air temperature measurement ranges from -50° to +100°C are possible; contact Campbell Scientific for more information.


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Data Loggers

Compatible Note
21X (retired)
CR10 (retired)
CR1000 (retired)
CR10X (retired)
CR200X (retired)
CR206X (retired)
CR23X (retired)
CR295X (retired)
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR9000 (retired)
CR9000X (retired)

Additional Compatibility Information


The HC2S3 should be housed in a 41003-5 10-plate naturally-aspirated solar radiation shield. This radiation shield mounts to a tripod or tower mast, crossarm, or user-supplied pole.

Articles and Press Releases

FAQs for

Number of FAQs related to HC2-S3-L: 9

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  1. It is possible that an older version of Short Cut is being used. Download the latest version of Short Cut.

  2. Campbell Scientific offers two filter tips:

    • The HC2S3-L comes with a polyethylene filter that provides protection against fine dust particles, doesn't absorb or retain water, and offers a good response time.
    • A Teflon filter can be ordered separately (pn 27755HC2S3 Replacement Teflon Filter). This filter has a smaller pore size (10 micron) that provides good protection against fine dust particles and salt (marine environments), but it has a slightly slower response time than the polyethylene filter.
  3. The sensor should not be cleaned with water. If the sensor is dirty, the filter should be changed or cleaned more frequently. A dirty filter can be cleaned with distilled water.

  4. To measure ambient temperature and relative humidity (RH), mount the HC2S3-L probe inside a 41003-5 or 41003-5A 10-Plate Radiation Shield. The 27731 hex plug is shipped with the HC2S3-L so that it can be used with older 10-plate radiation shield models. The 6-plate radiation shield (pn 41303-5A) cannot be used with the HC2S3-L.

  5. Most Campbell Scientific sensors are available as an –L, which indicates a user-specified cable length. If a sensor is listed as an –LX model (where “X” is some other character), that sensor’s cable has a user-specified length, but it terminates with a specific connector for a unique system:

    • An –LC model has a user-specified cable length for connection to an ET107, CS110, or retired Metdata1.
    • An –LQ model has a user-specified cable length for connection to a RAWS-P weather station.

    If a sensor does not have an –L or other –LX designation after the main model number, the sensor has a set cable length. The cable length is listed at the end of the Description field in the product’s Ordering information. For example, the 034B-ET model has a description of “Met One Wind Set for ET Station, 67 inch Cable.” Products with a set cable length terminate, as a default, with pigtails.

    If a cable terminates with a special connector for a unique system, the end of the model number designates which system. For example, the 034B-ET model designates the sensor as a 034B for an ET107 system.

    • –ET models terminate with the connector for an ET107 weather station.
    • –ETM models terminate with the connector for an ET107 weather station, but they also include a special system mounting, which is often convenient when purchasing a replacement part.
    • –QD models terminate with the connector for a RAWS-F Quick Deployment Station.
    • –PW models terminate with the connector for a PWENC or pre-wired system.
  6. Not every sensor has different cable termination options. The options available for a particular sensor can be checked by looking in two places in the Ordering information area of the sensor product page:

    • Model number
    • Cable Termination Options list

    If a sensor is offered in an –ET, –ETM, –LC, –LQ, or –QD version, that option’s availability is reflected in the sensor model number. For example, the 034B is offered as the 034B-ET, 034B-ETM, 034B-LC, 034B-LQ, and 034B-QD.

    All of the other cable termination options, if available, are listed on the Ordering information area of the sensor product page under “Cable Termination Options.” For example, the 034B-L Wind Set is offered with the –CWS, –PT, and –PW options, as shown in the Ordering information area of the 034B-L product page.

    Note: As newer products are added to our inventory, typically, we will list multiple cable termination options under a single sensor model rather than creating multiple model numbers. For example, the HC2S3-L has a –C cable termination option for connecting it to a CS110 instead of offering an HC2S3-LC model. 

  7. Note the difference between calibration and a field check. Calibration cannot be done in the field, as it requires an experienced technician and specialized equipment.

    Field checks of measurements can be done to determine if the data make sense with the real-world conditions. Follow these steps to field check a sensor:

    1. Find a second sensor of the same type as the installed sensor whose data is in question. The second sensor will be used as a benchmark sensor and should be known to be accurate or recently calibrated.
    2. At the site, take readings using both sensors under the same conditions. The best practice is to measure both sensors side-by-side at the same time. Note that the sensors will never have the exact same measurement.
    3. Depending on the sensor model, if the difference in the readings of the installed and benchmark sensors is greater than the sum of the accuracies for both sensors, either return the installed sensor to Campbell Scientific for calibration or replace the appropriate chip.
      • The 107, 108, 109, 110PV-L, and BlackGlobe-L temperature sensors can be calibrated.
      • The HC2S3-L and HMP155A-L temperature and relative humidity sensors can be calibrated.
      • The CS215-L has a replaceable chip for temperature and relative humidity. For more information, refer to the “Maintenance and Calibration” section of the CS215 instruction manual.
      • The HMP60-L has a replaceable chip for relative humidity only. For more information, refer to the “Maintenance” section of the HMP60 instruction manual.
  8. Many Campbell Scientific sensors are available with different cable termination options. These options include the following:

    • The –PT (–PT w/Tinned Wires) option is the default option and does not display on the product line as the other options do. The cable terminates in pigtails that connect directly to a data logger.
    • In the –C (–C w/ET/CS110 Connector) option, the cable terminates in a connector that attaches to a CS110 Electric Field Meter or an ET-series weather station.
    • In the –CWS (–CWS w/CWS900 Connector) option, the cable terminates in a connector that attaches to a CWS900-series interface. Connection to a CWS900-series interface allows the sensor to be used in a wireless sensor network.
    • In the –PW (–PW w/Pre-Wire Connector) option, the cable terminates in a connector that attaches to a prewired enclosure.
    • In the –RQ (–RQ w/RAWS Connector) option, the cable terminates in a connector that attaches to a RAWS-P Permanent Remote Automated Weather Station.

    Note: The availability of cable termination options varies by sensor. For example, sensors may have none, two, or several options to choose from. If a desired option is not listed for a specific sensor, contact Campbell Scientific for assistance.

  9. To incorporate a sensor that is compatible with wireless sensor interfaces into a wireless network, a CWS900-series wireless sensor interface is needed, as well as an A205 CWS-to-PC interface to configure it.