Weather Monitor II Specifications - Tech Info Document #1130

Document Number: 1130

A low cost weather station which will monitor inside temperature and relative humidity, plus outside temperature, wind speed and direction, barometric pressure, relative humidity (optional), and rainfall (optional).

Features & Construction

Compact LCD and keypad provide easy access to all sensor readings as well as wind chill, dew point, time, date, alarms, and highs and lows. Wind is displayed digitally and on a 16 point compass rose; all other functions displayed digitally. The unit comes with external temperature sensor and 25 foot of cable, anemometer/wind vane and 40 feet of cable, junction box, 8 feet long junction box cable, and an AC adapter. It has internal sensors for temperature, humidity, and barometric pressure. The rainfall and external relative humidity/temperature sensors are optional, and dew point cannot be calculated without the external humidity sensor. Highs and/or lows are recorded for all parameters, and corresponding alarms are available for them as well; except for pressure and dew point which have special trend and proximity alarms. There is also a regular time alarm.

Use & Operation

The anemometer is usually mounted on a roof or pole away from obstructions and up off the ground, and the temperature sensor is placed under an eave of a building or in a special weather shelter out of direct sunlight. The rain collector can be mounted on a roof or on or near the ground away from any interference, but it must be set level. The sensors can be extended with 40 foot long extension cables (weatherproof connections) which plug into the junction box. The junction box is commonly placed indoors, but could be placed outdoors if it is adequately sheltered from the elements (although this voids the warranty as Davis stipulates that it goes indoors). The standard 8 foot long junction box cable then connects it to the display, and it can be replaced by a longer cable up to 100 feet in length. The combination of junction box and sensor cables should not grossly exceed 160 feet or signal degradation will occur producing false readings. An AC adapter with a 6 foot cord provides power to the display, which is mounted on a wall or placed on a desk.

No calibration is necessary except for the orientation of the wind vane which can be accomplished with an inexpensive compass such as Suunto's A-1000 Basic Field Compass. The time, date, units of measure, and alarms are selected using the keypad. Monitoring begins upon power up, and with the optional Weatherlink, data can be displayed all at once on a PC or Macintosh computer, and logged for later retrieval and display or export to a spreadsheet.


Inside Temperature Range: 32-140F (0-60C) 
Accuracy: 1F (0.5C)
Outside Temperature Range: -50 to 140F (-45 to 60C) 
Accuracy: 1F (0.5C)
Wind Direction 16 points (22.5 each) on a compass rose
1 in digital display
Accuracy: 7
Wind Speed Maximum - 175 mph, 282 kph, 
152 knots, 78.2 m/s 
Accuracy: 5%
Wind Chill Range: -134 to 98F (-92 to 37C) 
Accuracy: 4F (2C)
Barometer Range - 26.00" to 32.00", 660.0 to 810.0mm, 880.0 to 1080.0 hPA
Accuracy: 0.05", 1.3mm, 1.7 hPA (at room temperature)
Relative Humidity Range: 0 to 100% 
Accuracy: 5% 
Dew Point Range: -99 to 140F (-73 to 60C) 
Accuracy: 4F (2C)
Rainfall Daily Range: 0 to 40.95" (0 to 819mm)
Total Range: 0 to 99.99" (0 to 9999mm)
Accuracy: (4% + 1 count) for rates from 0.01" to 2" per hour
                  (5% +1 count) for rates from 2" to 4" per hour
Resolution: 0.01" or 0.2 mm (user selectable)
Time 12 or 24 hour, 15 sec./month
Warranty One Year

Additional Information

A Weather Monitor may be powered remotely from a vehicle by a lighter adapter or another 9-12 volt power source such as a small battery (motorcycle) which does not exceed 200 miliamps (minimum 20 ma). The 9 volt backup battery will last for 2.5 days without the Weatherlink accessory and 1 day with it. Sensor and junction box cables can be extended to a length of about 160 feet total before signal degradation becomes a problem (the temp/humidity sensor requires a unique extension cable). The sensor extension cable connections are weatherproof but should not be buried, and it is often easier to extend the junction box cable instead of numerous sensor cables. The Rainfall sensor is optional! The Weather Monitor II requires the addition of the Weatherlink to be able to log data and view weather info from a PC.

Common Questions

Q. Can the Weather Monitor display be stationed outside?
A. Not unless it and the power adapter are kept in a weatherproof enclosure and sheltered from direct sun. But this is not in line with the manufacturer's installation directions so the customer would be responsible for the unit.
Q. How often do the highs and lows reset?
A. They are reset manually by the user whenever desired. Highs and lows are recorded along with the date and time they occurred.
Q. Will the Weather Monitor store rainfall amounts by time intervals?
A. No, only the Weatherlink has that capability. The Weather Monitor stores daily total and accumulated rainfall since the last reset.
Q. Can the junction box be mounted outside?
A. It is not recommended, nor is it shown that way in the installation manual, but it is probably safe to mount it in a very protected location outdoors. Should a customer do this however it does void the warranty due to installation inconsistent with the manufacturer's instructions.

Ordering Information

31126  Weather Monitor II
31132  40 ft. Sensor Extension Cable
31129  Rain Collector II English Version (0.01" increments)
110065 Rain Collector II Metric Version (0.2mm increments)
110056 External Temp/humidity Sensor
31130 40 ft. Temp/humidity Sensor Extension Cable
110054 Lighter Adapter w/4.5 ft. cord
110062  25 ft. Junction Box Cable
110063 50 ft. Junction Box Cable
110064  100 ft. Junction Box Cable


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Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.