Going to 1 would restart the initial value. Going to 2, data will be stored as "increased/decreased" (by a known amount... degree, tenth of a degree??) form, taking up bits, not in a whole value taking up bytes. Time interval is known.
This is pseudocode... my guess is one... for "sameTemp" then all the data is "offset from initial value at a known interval" Greatest range of temperature (worldwide) in a day is 57c. Extreme temperature ranges where humans using computers live is 20c.