Traveling to Japan? Skip the Ssummer Mmonths Traveling to Japan? Skip the summer months

No need to capitalise (but eg you might capitalise Golden Week, since it is a proper noun)

The long holidays, week known as Golden Week, haves begun, and the traffic was unusually heavy even early this morning. The holiday week known as Golden Week has begun, and the traffic was unusually heavy even early this morning.

"long holidays" makes me think of multiple holidays that are long. A good English phrasing is difficult, but "holiday week" or "holiday period" seems ok

The long holidays, known as Golden Week, have begunbegan today, and the traffic was unusually heavy even early this morning. The long holidays, known as Golden Week, began today, and the traffic was unusually heavy even early this morning.

I changed it so the verb tenses are the same between "begun" and "the traffic was". You could alsosay "have begun... the traffic has been...".

April and May are the best months for travelling in Japan, so it makes sense that our national holidays are set in this seasonperiod. April and May are the best months for travelling in Japan, so it makes sense that our national holidays are set in this period.

I use "period" instead because you mentioned months instead of a season like spring.

After this period, summer becomes more intense every year, sometimes almost unbearably hot, and it's been getting worse every year. After this period, summer becomes more intense, sometimes almost unbearably hot, and it's been getting worse every year.

It's kind of awkward because it switches time frames from months (after this period) to year-to-year (more intense every year), so I reworded it.

After this period, is summer becomes, which has been getting more intense every year, sometimes almost unbearably hot. After this period is summer, which has been getting more intense every year, sometimes almost unbearably hot.

I changed things so the ideas flowed better.

When foreign visitortourists ask me about the best time to come to Japan, I always tell them to avoid the period between June toand September. When tourists ask me about the best time to come to Japan, I always tell them to avoid the period between June and September.

I changed it to "tourists" because it'd be more common wording, and "foreign" for people can sometimes be taken as rude. If they aren't tourists, you could say "people from other countries" or something like that.

The summer here is dangerous enough to be life‑threatening, especially for uninformed visitors. The summer here is dangerous enough to be life‑threatening, especially for uninformed visitors.

I really hope visitors can enjoy Japan comfortably, not instead of returning home with memories of how harsh the summer felt. I really hope visitors can enjoy Japan comfortably instead of returning home with memories of how harsh the summer felt.

I'm not sure why but the "I hope ..., not ..." construction doesn't feel right to me here. I think because "return home with..." doesn't follow naturally from "I hope visitors..." [EG the full phrase would then be 'visitors return home with memories...' which is odd-feeling]

I really hope visitors can enjoy Japan comfortably, and not return home with memories of how harsh the summer felt. I really hope visitors can enjoy Japan comfortably, and not return home with memories of how harsh the summer felt.

or "instead of returning"