This product is no longer available and has been replaced by: EE181-L.
HMP45C-LC Temperature and Relative Humidity Probe
Services Available
Repair No
Calibration Yes
Free Support No


The HMP45C-LC is a rugged, accurate temperature and relative humidity probe. The sensor measures relative humidity over the 0 to 100% RH range and temperature over the -40° to +60°C range.

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Benefits and Features

  • Well-suited for long-term, unattended applications
  • Accurate and rugged
  • Configured for use with the MetData1 Weather Station or CS110 Electric Field Meter


Detailed Description

This version of the HMP45C has a connector instead of pigtails for connecting the sensor to a MetData1 Weather Station or CS110 Electric Field Meter. The probe uses a HUMICAP capacitive polymer H chip to measure relative humidity, and a PRT to measure temperature. Relative humidity range is 0 to 100% RH, and temperature range is -40° to +60°C. A solar radiation shield is required if the probe will be exposed to sunlight.


Supply Voltage 12 Vdc nominal (typically powered by datalogger)
Current Consumption ≤ 4 mA (active)


Temperature Sensor 1000 ohm Platinum Resistance Thermometer
Measurement Range -39.2° to +60°C
Output Signal Range 0.008 to 1.0 V
Accuracy See graph in HMP45C product brochure.

Relative Humidity

Sensor Vaisala’s HUMICAP H-chip
Measurement Range 0.8% to 100% RH (non-condensing)
Output Signal Range 0.008 to 1 Vdc
Accuracy at 20°C
  • ±1% RH (against factory reference)
  • ±2% (0% to 90% range) field-calibrated against references
  • ±3% (90% to 100% range) field-calibrated against references
Temperature Dependence ±0.05% RH/°C
Long-Term Stability Typically, better than 1% RH per year
Response Time 15 seconds with membrane filter (at 20°C, 90% response)
Settling Time 500 milliseconds


The connector can be attached to the CS110 Electric Field Meter or MetData1 Weather Station. The CS110 has a CR1000 and the MetData1 has an on-board CR10X.


The HMP45C-LC 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.

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