there are so many bike seats for babies

I was thinking of buying one but concern about safety and weather.
Our climate isn't always suitable for riding out without shade. And there's no bike track around the city.
Summer is too long and hot here. Soon baby will be too big to be put into the seat, maybe just one summer after.
So we'd rather forgo this option.
Tot 2.5 year old should be able to ride a tricycle, we have just one year to go!
Isn't it better that she can ride by herself, along with mommy's big bike?