Short answer
The best time to visit the Azores is generally from June to September, when temperatures are mild to warm and rainfall is lower. July and August are the busiest and most expensive months. Spring and autumn offer fewer crowds and lush landscapes but more unpredictable rain. Winter is quieter, cheaper and good for whale watching, though some trails and ferries may be limited.
General information, not legal or tax advice. Rules and amounts change: confirm with official sources.