:: Product Information

Kestrel® 4300 Construction Weather Tracker



Kestrel 4300 Measures

Evaporation rate
Relative humidity in %
Wind speed (current, average, and maximum)
Temperature in °F or °C  
Barometric pressure
Heat stress index  
Wet bulb temperature
Density altitude    

Calculates Evaporation Rate

The new Kestrel 4300 Construction Weather Tracker measures and displays evaporation rate — a function of relative humidity, temperature and wind speed. Evaporation rate is a critical environmental indicator that concrete contractors use to ensure they avoid plastic shrinkage cracks in concrete installations especially concrete flatwork. Plastic shrinkage cracks occur when the surface of the concrete dries too quickly and shrinks before the bed has cured enough to resist cracking. This is especially relevant in specialty applications like decorative concrete, Ready Mix Concrete (RCM) and Tilt-up concrete.

Helps Prevent Plastic Shrinkage Cracks

Plastic shrinkage cracks can be prevented by properly assessing the weather and the fresh concrete conditions. Previously, construction contractors used a Kestrel Meter to measure the relevant conditions, then referenced an American Concrete Institute chart to calculate the evaporation rate. The new Kestrel 4300 Construction Weather Tracker does the work for them! The user simply enters the concrete temperature (obtained via an infrared thermometer or probe thermometer*) and the 4300 calculates the evaporation rate instantly. In addition to evaporation rate, the Kestrel 4300 remains the perfect rugged all-purpose construction weather tool, measuring and logging the following relevant weather conditions right where the workers and equipment are operating.

For maximum accuracy when measuring the evaporation rate:

1.Measure the concrete temperature via an infrared or probe thermometer
2.Enter the concrete temperature into the Kestrel
3.Position the unit facing into the wind, 20 inches above the concrete
4.Shade the Kestrel's thermistor (temperature sensor) so it is not in direct sunlight

For the best accuracy, use the Kestrel's convenient averaging mode to average the evaporation rate over the recommended 6-10 seconds.

Documents Work Conditions

Many construction applications require documentation of conditions, which is quick and easy with the Kestrel PC Interface and accompanying software. Use the 4300's 1800 data-point log to document that work was done during the appropriate conditions, then upload the data to a PC with the Kestrel PC Interface. The Kestrel Communicator software makes long-term storage, in-depth analysis and detailed charting of stored data a breeze.
Kestrel's Mini Tripod is a great companion for the 4300—it measures 15 inches tall, positioning the Kestrel 4300 20 inches above the concrete, which is ideal for measuring the conditions that contribute to plastic shrinkage cracks.

Every Kestrel is individually calibrated to NIST-traceable standards and comes with a free Certificate of Conformity. Individual NIST certificates and recalibration are also available.

Kestrel 4300 Features

Waterproof and floats
Backlight for low light conditions
Data logger (automatic and manual)
Customizable data storage – 3600 data points
Multi-Function 3-line display
Convenient averaging mode
Data charting
Humidity sensor can be recalibrated in the field with our Relative Humidity Calibration Kit.
User-replaceable impeller
Flip-top impeller cover
Upload to a computer (with optional interface)
Five languages (English, French, Spanish, German, and Italian)
US Patent Nos. 5,783,753 and 5,939,645 and 6,257,074
5-year warranty
Assembled in the USA

Kestrel 4300 Includes

Soft carry pouch
Neck lanyard
Batteries – 2 AAA
Kestrel Certificate of Conformity


Response Time


Operational Range



Specification Range

Wind Speed
(Air Velocity)
1 second  


0.4 to 60.0 m/s


Larger of 3% of reading or least significant digit

0.4 to 40.0 m/s


59 to 11,948 ft/min


59 to 7877 ft/min


1.0 to 218.0 km/h


1.0 to 144.0 km/h


0.8 to 135.0 mph


0.8 to 89.0 mph


0.6 to 118.3 kt


0.6 to 78.0 kt


0 to 12 B


0 to 12 B

1 inch diameter impeller with precision axle and sapphire bearings.  Off-axis accuracy -1% @ 5º off-axis; -2% @ 10º; -3% @ 15º.  Calibration drift < 1% after 100 hours use at 16 MPH / 7 m/s.  Sustained operation above 60 MPH / 27 m/s will wear impeller rapidly and may cause destruction of impeller.  Replacement impeller (NK PN-0801) may be field-installed without tools (US Patent 5,783,753).

1 second


-49.0 to 257.0 °F


1.8 °F

-20.0 to 158.0 °F


-45.0 to 125.0 °C


1.0 °C

-29.0 to 70.0 °C

Measures air, water and snow temperature.  Thermally isolated, hermetically sealed, precision thermistor mounted externally (US Patent 5,939,645).  Calibration drift negligible.

Relative Humidity
1 minute 


0.0 to 100.0 %


3.0 %RH

 5.0 to 95.0 % non-condensing

Polymer capacitive humidity sensor mounted in thin-walled chamber external to case for rapid, accurate response (US Patent 6,257,074).  (To achieve stated relative humidity accuracy, unit must be permitted to equilibrate to external temperature when exposed to large, rapid temperature changes and must be kept out of direct sunlight.)  Calibration drift +/- 2% over 24 months. Relative humidity may be recalibrated at factory or in field using Kestrel Humidity Calibration Kit (NK PN-0802).

Evaporation Rate
1 second


0.00 to 1.00 lb/ft2/hr


Typical: ±0.02 lb/ft2/hr

0.00 to 1.00 lb/ft2/hr


0.00 to 5.00 kg/m2/hr


Typical: ±0.1 kg/m2/hr

0.00 to 5.00 kg/m2/hr

Calculated from the primary measurements of wind speed, air temperature, relative humidity and concrete temperature.  Requires user measurement and entry of concrete temperature obtained with an accurate IR or probe thermometer (°F or °C, not included with Kestrel 4300). For maximum accuracy, readings should be taken 20 inches above pour surface with the thermistor shaded, and averaged for 6-10 seconds using built-in averaging function. Maximum accuracy: ±0.06 lb/ft2/hr or  ±0.3 kg/m2/hr.

1 second  (mb & PSI 4000 model only)


8.86 to 32.48 inHg


0.05 inHg

At 77.0 °F, <19,700 ft

hPa / mb

300.0 to 1100.0 hPa / mb


1.5 hPa / mb

At 25.0 °C, <6,000 m


4.4 to 16.0 PSI


0.1 PSI

At 77.0 °F, <19,700 ft

Monolithic silicon piezoresistive pressure sensor with second-order temperature correction.  Maximum error beyond specified temperature, +/- 0.09 inHg / 3.0 hPa.  Calibration drift typically -0.03 inHg / -1.0 hPa per year.  Pressure sensor may be recalibrated at factory or in field.

1 second  


-6000 to 30000 ft


50 ft

At 77.0 °F, <19,700 ft. Max error +/- 98 ft


-2000 to 9000 m


15 m

At 25.0 °C, <6,000 m.  Max error +/- 30 m

Temperature compensated pressure (barometric) altimeter. 

Wind Chill  
1 second  


0.7 to 135.0 MPH, -49.0 to 257.0 °F


1.8 °F

1.8 to 89.0 mph, -50.0 to 50.0 °F


0.4 to 60.0 m/s, -45.0 to 125.0 °C


1.0 °C

0.4 to 40 m/s, -45.6 to 10.0 °C

Calculated from the primary measurements of wind speed and temperature.  Utilizes the NWS Wind Chill Temperature (WCT) Index, revised 2001, with wind speed adjusted by a factor of 1.5 to yield equivalent results to wind speed measured at 10 m above ground.  (Specification temperature limits established by WCT Tables.)

Heat Index  
1 minute  


0.0 to 100.0 %RH, -49.0 to 257.0 °F


3.6 °F

70.0 to 130.0 °F, 0 to 100% RH


0.0 to 100.0 %RH, -45.0 to 125.0 °C


2.0 °C

21.1 to 54.4 °C, 0 to 100 %RH

Calculated from the primary measurements of temperature and relative humidity.  Utilizes the NWS Heat Index (HI) tables.  (Specification temperature limits established by HI tables.) 

1 minute  


0.0 to 100.0 %RH, -49.0 to 257.0 °F


3.6 °F

-20.0 to 158.0 °F, 20.0 to 95.0% RH


0.0 to 100.0 %RH, -45.0 to 125.0 °C


2.0 °C

-29.0 to 70.0 °C, 20.0 to 95.0 %RH

Calculated from the primary measurements of temperature and relative humidity. Temperature to which the air would need to be cooled at a constant pressure to become saturated.

Wet Bulb Temperature 
1 minute  


-49.0 to 257.0 °F, 0.0 to 100.0 %RH,                  8.86 to 32.48 inHg


3.6 °F

32.0 to 100.0 °F, 5.0 to 95.0% RH,                            8.86 to 32.48 inHg, <19700 ft


-45.0 to 125.0 °C, 0.0 to 100.0 %RH,                               300.0 to 1100.0 hPa


2.0 °C

0.0 to 37.8 °C, 5.0 to 95.0 %RH,                                      -2000.0 to 9000.0 hPa, <6000 m

Calculated from the primary measurements of temperature, relative humidity and pressure. Temperature indicated by a wet bulb psychrometer.

Density Altitude  
1 second  


-49.0 to 257.0 °F, 0.0 to 100.0 % RH,                   8.86 to 32.48 inHg



32.0 to 100.0 °F, 5.0 to 95.0 %RH,                                   8.86 to 32.48 inHg, <19700 ft


-45.0 to 125.0 °C, 0.0 to 100.0 %RH,                       300.0 to 1100.0 hPa



0.0 - 37.8 °C, 5.0 to 95.0 %RH,                                           -2000 to 9000 hPa, <6000 m

Calculated from the primary measurements of temperature, relative humidity and pressure.  Air density converted to equivalent sea level elevation at the International Standard Atmosphere.

Max/Avg Wind Speed (Air Velocity)

One-button clear and restart of Max Wind Gust and Average Wind measurement.

Data Storage / Display

Minimum, maximum, average and logged history stored and displayed for every measured value. 3600-point data logger with graphical display. Auto data storage; interval settable from 2 seconds to 12 hours. Manual data capture.  

Data Upload

Requires optional PC interface (NK PN-0830) and provided software. RS-232 connection with USB adapter available.


Multifunction, multi-digit programmable dot-matrix display.

Display Update

1 second.

Display Backlight

Aviation green electroluminescent backlight. Automatic or manual activation.

Clock / Calendar

Real-time hours:minutes:seconds clock, calendar, automatic leap-year adjustment.

Operational Temperature Range
(LCD and Batteries)

The operational temperature range of the liquid crystal display and batteries is 14° F to 131° F / -10 °C to 55 °C. Beyond the limits of the operational temperature range, the unit must be maintained within range and exposed for minimum time necessary to take reading.

Storage Temperature

-22 °F to 140 °F / -30 °C to 60 °C.

Auto Shutdown

User-selectable:  15 or 60 minutes with no key presses or disabled.


English, French, German, Italian, Spanish.


CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge).  


AAA Alkaline, two, included. Average life, 400 hours of use, +/-depending on backlight use.


Waterproof (IP67 standard). Drop-tested (MIL.STD.810F; unit only. Substantial impact may damage replaceable impeller.).


Unit 5.0 x 1.8 x 1.1 in / 12.7 x 4.5 x 2.8 cm.


Unit 3.6 oz / 102 g.

Kestrel Meters are designed and manufactured at NK’s facility in Boothwyn, Pennsylvania, and are individually calibrated at the time of manufacture. Every Kestrel Meter comes with a Certificate of Conformity to document the unit’s accuracy—all Kestrel measurements are traceable to the National Institute of Standards and Technology, ensuring the highest level of reliability. Additional NIST Calibration and Certification services are available.

 Producing Area:USA

related products

Tel: (852) 6852 7220
Email: Sales@qudao.com.cn
© Channel Technology Group HK Limited All Rights Reserved.