NOTE: When you restart your WeatherMate, it will default to
the last mode and unit used.
TAKING MEASUREMENTS: Hold or place the meter so
airflow enters the vane (impeller) from the rear of the unit.
When holding the meter, hold it at arm’s length, away from
your body. CAUTION: The WeatherMate is very accurate at
low and mid-range air speeds. Consistent use at very high
speeds, ie. from the window of a fast-moving car, will
damage the impeller’s bearing and reduce accuracy. See
below for impeller replacement.
WINDSPEED AVERAGE MODE: You may select average
readings over 10 seconds. Press the MODE button repeatedly
until the AVG icon appears.
MAXIMUM WINDSPEED HOLD: Press the MODE button
repeatedly until the MAX icon appears. After a measurement
session, the LCD will show the highest windspeed measured
since selecting the MAX icon. Press the MODE button
repeatedly to return to current windspeed or other options.
TAKING DELTA T: Press the MODE button repeatedly until
the delta T icon appears. Delta T is a measure of
atmospheric moisture that can provide a more useful
indication of the evaporation rate than Relative Humidity
alone. Delta T is defined as the difference between the dry
bulb and wet bulb temperatures. (This calculation takes
place automatically in your WeatherMate WM300.) When
applying chemical products, there can be problems with drift
and chemical efficacy if Delta T is too high or too low. This is
because either too much or too little evaporation can alter
the behavior of the sprayed droplets (during application or
after reaching the target). A Delta T value of 2-8 C generally
