If you're not looking for true 'compression' you could just look into
encoding your data differently. One thing that might make sense for
something like temperature is just to record the differences. Then,
say, use 4 bits signed for these values instead of a full 8 bits, make
some value represent 'out of range' as a marker that the full reading
follows.You end up doing a fair amount of bit shifting but it can save
a fair bit of space. Obviously, this taken to the extreme is a
compression algorithm. Also make sure you're not wasting space on
storing 'useless' data, if the range of your wind direction is just
the 4 cardinal directions, don't waste 8 bits(or more) to store it.

-Steve
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