The short answer is that we run our island-hopping trips from April to mid-October, with June to September being the high season. Spring and early summer is best for whales, late summer best for wine. The hydrangeas start flowering around May and are at their best until September.
If you are looking for winter travel, please see our dedicated Winter in São Miguel itinerary. The Azores' biggest island makes for a lovely winter getaway.
The more detailed 'when to go' answer is...
Spring
Spring equates to April through June and is a wonderful time of the year to visit the Azores.
At this time of the year, the temperatures are becoming more mild, the days are getting longer, the sea is getting warmer and calmer and the winds tend to lessen. Flowers are beginning to bloom and the migratory whale species are beginning to arrive.
The general rule is, the later in spring you go, the better the conditions become. The hydrangeas are really hitting their stride in late May and June. The whales are here in greatest numbers around those times too. As spring goes on, the tea harvest in São Miguel really gets going too. As sea temperatures rise, you can also start to swim in the natural seawater pools and off of some beaches.
Summer
The summer is generally considered to be July through September, though for many locals they include June in their thinking when they talk about the summer.
This is historically the warmest, driest and calmest time of the year. Sea temperatures are at their highest, usually in the mid-twenties, but they can get up to 27 degrees in extremely warm years. The summer is also the most humid time, which can make hikes a little sweaty. Keep in mind though that summer temperatures in the Azores are nothing like the scorching levels reached on the Portuguese mainland. It is therefore a great summer destination.
At this time of the year, you can still catch the whales before most leave the archipelago. The hydrangeas and other flowers are blooming away beautifully (though waterfalls are at their tamest). It’s a lovely time to swim in the many natural seawater pools dotted around the islands, though they may of course be a little busy with locals.
In the vineyards of Pico, the grapes will be getting nice and plump ahead of the harvest in late August and early September, a very photogenic time to be on the island. Likewise in São Jorge, you may see coffee beans drying in the sun following the annual harvest. Summer is also festival time across the archipelago, with a plethora of music and cultural events to enjoy.
You will also have the greatest choice of flight connections in the summer, particularly for direct flights into São Miguel from London or North America.
In summer it will be busier than usual in some hotspots on São Miguel. But it's never difficult to leave these behind. For other islands, the increase in visitor numbers is not really noticeable simply because there is less tourism infrastructure and capacity. But it does mean you absolutely must plan ahead to secure accommodation and activities as these are small-scale, just the way we like it. The earlier the better, but ideally we will have things booked up by January or February.
Fall
Fall is a fleeting time in the Azores, generally considered to be October and November, but really we’re talking about October up until the clocks go back. That event marks a step change signalling the arrival of winter for a lot of locals. Losing the hour shortens the days going into November, with sunset usually around 18:00.
October is a transition month. The weather is less stable than in summer, which doesn’t mean you lose entire days to rain, but it’s when the notion of ‘four seasons in a day’ is ramped up to the max. It is therefore a time of rainbows.
Temperatures are generally still very pleasant, in the high teens or low twenties. Sea temperatures hover around the same mark, but you do have to exercise caution as the ocean becomes a little less placid. October is a wonderful time of the year for the hot springs of São Miguel. As we roll into November, you see a lot of fall colors as deciduous trees begin to shed their leaves. It isn’t New England in fall, but it can be an impressive sight.
There is a definite ‘after the party’ feeling as October goes on. The migratory whales have left, the grapes on Pico have been harvested, the crowds have thinned and some seasonal restaurants are closing. The flip side to that is that things are generally calmer and quieter as everyone takes a breath after the (relative) busyness of the summer.