Days of the week :
Weekdays Weekend days
Monday , Tuesday, Wednesday, Saturday, Sunday
*** The days of the week always start with a capital letter.
He is playing football on Sunday.
Months and Seasons
These are the twelve months of the year :
January February March April May June
July August September October November December
*** Months always begin with a capital letter.
My birthday is in February.
These are the four seasons :
winter spring summer fall/autumn
The four seasons don't need a capital letter.
In winter, we go skiing.