Tokyo experiences all four seasons of weather. From cold winters to overbearingly hot and humid summers.
Yes, in the winter there is snow. It’s not terrible (usually) and it’s cold — but not arctic frigid cold.
Summers are the flip opposite though. Hot. Humid. Annoyingly so. I don’t recommend coming to Tokyo is the middle of summer.
Early-mid Spring and early Fall are where it’s at. The temperature is just right.
Expect it to rain though. And keep an eye out for typhoons. They happen frequently but aren’t something to worry about too much.
They will put a damper on your travels though.