What is the range and precision of the temperatures measured?
(which sensor do you use?)
You could "double" the storage by compressing the values into an uint8_t
That will give you 256 unique values.
If the range is limited e.g. to 10-70 degrees Celsius.
you could store the values in an uint8_t with 0.25 degree C precision.
If the range is limited e.g. to -20 - 100 degrees Celsius.
you could store the values in an uint8_t with 0.5 degree C precision.
Or in Fahrenheit you could do -30 - 212 F in an uint8_t with 1 degree F precision.
If temperatures fluctuate minimal you could apply run length compression.
Run length: instead of 23 23 23 23 23 24 25 25 25 you store 5, 23, 1, 24, 3, 25
A hardware option might be to use an FRAM for the data.
Advantage is that data is stored non-volatile and is kept over restarts.
A 32 K FRAM could store ~16000 measurements
(enough for ~10 days a measurement per minute)