La Crosse Technology WS-9031U Instruction Manual page 33

The icons displayed forecasts the weather in terms of getting better or worse
and not necessarily sunny or rainy as each icon indicates. For example, if the
current weather is cloudy and the rainy icon is displayed, it does not mean that
the product is faulty because it is not raining. It simply means that the air
pressure has dropped and the weather is expected to get worse but not
necessarily rainy.
Note:
After setting up, readings for weather forecasts should be disregarded for the
next 12-24 hours. This will allow sufficient time for the Weather Projection
Station to collect air pressure data at a constant altitude and therefore result in
a more accurate forecast.
Common to weather forecasting, absolute accuracy cannot be guaranteed.
The weather forecasting feature is estimated to have an accuracy level of
about 75% due to the varying areas the Weather Projection Station has been
designed for use. In areas that experience sudden changes in weather (for
example from sunny to rain), the Weather Projection Station will be more
accurate compared to use in areas where the weather is stagnant most of the
time (for example mostly sunny).
If the Weather Projection Station is moved to another location significantly
higher or lower than its initial standing point (for example from the ground floor
to the upper floors of a house), discard the weather forecast for the next 12-24