The hair & clothing could be anywhere from the late 1950s to the mid 1960s depending on the location. But the buildings & structures in the background do tell a lot. They weren't building new homes in cities much those days. New buildings in cities were mostly commercial, industrial, & public buildings.
The buildings are newer & too close together to be rural, so this is a suburban area. From the style & types of structures, the gate, fence, the gutters, & the sidewalk it appears to be early to mid 1960s. It is the style of property for someone with above average income in the suburbs. The hair & clothes are what would have been fashionable in those days. Even in clips of the early Beatles concerts you would see many girls wearing almost this same type of outfit & hair. Above average income people tend to try to be more "fashionable" while the rest of us wore "hand me downs", & our parents cut our hair.
Home air conditioning in those days was bulky, heavy, noisy, inefficient, & frequently broke down. So many even wealthy or suburban families wouldn't use them. The shorter hair was more comfortable in hot climates or during the hot summer. The bugs were a lot thicker in the suburbs & rural areas too. Sweating in long hair attracted bugs more than short hair, & bugs get tangled in long hair, which is a real icky or frightening thing for most girls.
There was also the myth that is still around today that long hair attracts lice & they like it more, so in areas where they heard there was lice going around, the girls had their hair short. It turns out though, head lice don't care how long your hair is. Unless you're gonna shave your head bald down to the skin, lice are just as happy in hair that's only 1/4 inch long as they would be if your hair is 2 feet long.