Storing dates and temperatures (minimum and maximum)

years 1900 to 2099
months 1 to 12
days 1 to 31
min and max temperature -200 to +200

struct recording
{ int year, month, day, min_t, max_t; };

each recording occupies 20 bytes (160 bits)

struct recording
{ short int year, min_t, max_t;
  unsigned char month, day; };

now each recording occupies 8 bytes (64 bits)

but
   year   requires only  8 bits
   month  requires only  4 bits
   day    requires only  5 bits
   min_t  requires only  9 bits
   max_t  requires only  9 bits
                       ---------
                  total 35 bits

How can we program that bit squeezing?