Kestrel: 4500 Pocket Weather Meter, Yellow

Kestrel's flagship meter.

It packs down into a 2 x 6 inch pouch and weighs under 8 ounces
Displays exterior temperature, humidity, wind direction and more, quickly and accurately
Flip-top impeller cover allows use of other functions while protecting the impeller
Customize screens to display user-selected measurements
Humidity sensor can be recalibrated in the field

For years our customers have been asking for an affordable hand-held device that measures wind direction along with wind speed. The Kestrel 4500 does just that with its built in digital compass. But it doesn’t stop there. It also calculates crosswind and headwind/tailwind with reference to a user-set target heading, and stores the information along with all the other environmental readings in its 1400 data point memory.

Measures:

Heading (true & magnetic)
Wind direction
Crosswind
Headwind/tailwind
Altitude
Pressure trend
Barometric pressure
Relative humidity in %
Heat stress index
Dewpoint
Density altitude
Wind chill
Air, water, and snow temperature °F or °C
Current, average, and maximum air velocity
Wet Bulb temperature

Features:

Waterproof and floats
Time and date
Easy- to-read backlit display
Data Logger (automatic and manual)
Customizable data storage - 1400 data points
Minimum, Maximum and Average values
Multi-Function 3-line display
Graph and recall trends
User-replaceable impeller
Data charting
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

Includes:

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

Click Here for Full Specifications

Measurement Response Time	Units	Operational Range	Resolution	Accuracy (+/-)	Specification Range
Wind Speed 1 second	m/s	0.4 to 60.0 m/s	0.1	Larger of 3% of reading or least significant digit	0.4 to 40.0 m/s
	ft/min	59 to 11,948 ft/min	1		59 to 7877 ft/min
	km/h	1.0 to 218.0 km/h	0.1		1.0 to 144.0 km/h
	mph	0.8 to 135.0 mph	1		0.8 to 89.0 mph
	knots	0.6 to 118.3 kt	0.1		0.6 to 78.0 kt
	Beaufort	0 to 12 B	0.1		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).
Wind Direction / Forward Heading 1 second	°	360°	1	5°	0 to 360°
	Cardinal Points	360°	16 Points	5°	0 to 360°
	2-axis solid-state magnetoresistive sensor mounted perpendicular to unit plane to permit operation while measuring wind speed. Declination/variation adjustable for True North readout. Accuracy of measurements dependent upon unit's vertical position. Self-calibration routine eliminates magnetic error from batteries or unit and must be run after every full power-down (battery removal or change).
Temperature 1 second	°F	-49.0 to 257.0 °F	0.1	1.8 °F	-20.0 to 158.0 °F
	°C	-45.0 to 125.0 °C	0.1	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	%RH	0.0 to 100.0 %	0.1	3.0 %RH	5.0 to 95.0 % non-condensing
Relative Humidity 1 minute	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).
Pressure 1 second (mb & PSI 4000 model only)	inHg	0.3 to 32.5 inHg	0.01	0.05 inHg	At 77.0 °F, 22.1 to 32.5 inHg
	hPa / mb	10.0 to 1100.0 hPa / mb	0.1	1.5 hPa / mb	At 25.0 °C, 750 to 1100 hPa / mb
	PSI	0.15 to 16.0 PSI	0.01	0.02 PSI	At 77.0 °F, 10.9 to 16.0 PSI
	Monolithic silicon piezoresistive pressure sensor with second-order temperature correction. Maximum error over temperature range 32 to 158 °F (0 to 70°C) , +/- 0.06 inHg / +/-2.0 hPa. Calibration drift typically -0.03 inHg / -1.0 hPa per year. Pressure sensor may be recalibrated at factory or in field.
Altitude 1 second	ft	-6000 to 30000 ft	1	50 ft	At 77.0 °F, <19,700 ft. Max error +/- 98 ft
	m	-2000 to 9000 m	1	15 m	At 25.0 °C, <6,000 m. Max error +/- 30 m
	Temperature compensated pressure (barometric) altimeter.
Crosswind Headwind, Tailwind 1 second	mph	0.8 to 135.0 mph	1	5%	8.5 to 89.0 mph
	ft/min	59 to 11,880 ft/min	1	5%	750 to 7832 ft/min
	km/h	1.0 to 217.3 km/h	0.1	5%	13.7 to 143.2 km/h
	m/s	0.4 to 60.0 m/s	0.1	5%	3.8 to 40.0 m/s
	knots	0.6 to 117.3 kt	0.1	5%	7.4 to 77.0 kt
	Calculated from the primary measurements of wind speed, wind direction and target heading. Auto-switching headwind/tailwind indication. Ranges expressed refer to primarywind speed.
Wind Chill 1 second	°F	0.7 to 135.0 MPH, -49.0 to 257.0 °F	0.1	1.8 °F	1.8 to 89.0 mph, -50.0 to 50.0 °F
	°C	0.4 to 60.0 m/s, -45.0 to 125.0 °C	0.1	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	°F	0.0 to 100.0 %RH, -49.0 to 257.0 °F	0.1	3.6 °F	70.0 to 130.0 °F, 0 to 100% RH
	°C	0.0 to 100.0 %RH, -45.0 to 125.0 °C	0.1	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.)
Dewpoint 1 minute	°F	0.0 to 100.0 %RH, -49.0 to 257.0 °F	0.1	3.6 °F	-20.0 to 158.0 °F, 20.0 to 95.0% RH
	°C	0.0 to 100.0 %RH, -45.0 to 125.0 °C	0.1	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	°F	-49.0 to 257.0 °F, 0.0 to 100.0 %RH, 8.86 to 32.48 inHg	0.1	3.6 °F	32.0 to 100.0 °F, 5.0 to 95.0% RH, 8.86 to 32.48 inHg, <19700 ft
	°C	-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa	0.1	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	ft	-49.0 to 257.0 °F, 0.0 to 100.0 % RH, 8.86 to 32.48 inHg	1	246	32.0 to 100.0 °F, 5.0 to 95.0 %RH, 8.86 to 32.48 inHg, <19700 ft
	m	-45.0 to 125.0 °C, 0.0 to 100.0 %RH, 300.0 to 1100.0 hPa	1	75	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), Crosswind, Headwind/Tailwind	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. 1400-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.
Display	Multifunction, multi-digit programmable dot-matrix display.
Display Update	1 second.
Display Backlight	Choice of aviation green or visible red 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.
Languages	English, French, German, Italian, Spanish.
Certifications	CE certified. Individually tested to NIST-traceable standards (written certificate of tests available at additional charge).
Batteries	AAA Alkaline, two, included. Average life, 400 hours of use, +/-depending on backlight use.
Environmental	Waterproof (IP67 standard). Drop-tested (MIL.STD.810F; unit only. Substantial impact may damage replaceable impeller.).
Dimensions	Unit 5.0 x 1.8 x 1.1 in / 12.7 x 4.5 x 2.8 cm.
Weight	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.