The charter season on the Slovenian coast runs from May into early October. The Gulf of Trieste is shallow, with an average depth of under 20 metres, so its water warms fast in early summer and cools quickly again in autumn. Three winds shape the sailing. On summer afternoons a sea breeze from the west or north-west, which sailors here call the maestral, fills in and usually fades by evening. The bora, or burja, is a cold, gusty north-easterly that pours down from the Karst, strongest and most frequent in the cooler months, and the jugo, from the south-east, brings cloud, rain and a rising sea.

APRIL AND MAY

17–22°C

Best for cliff walks and quiet old towns

Spring days are mild, the Karst turns green and the coastal towns have plenty of space. The sea is still cool, at around 14°C in April and 17–19°C as May ends, which makes spring better suited to walks on the Strunjan cliffs, rides along the Parenzana and a visit to the Škocjan Caves than to long swims. Now and then the bora still blows in, cold and hard, for a day or two.

JUNE

24–27°C

Best for a fast-warming sea and evening light

The shallow gulf warms quickly through June, from around 20°C at the start of the month to 23°C or more by its end, and by late June the sun does not set until almost nine in the evening. The maestral blows on most afternoons, good for a sail across to Trieste or down the coast of Istria. Salt crystals start to form in the Sečovlje pans in the middle of the month, and the beaches are busy without yet being full.

JULY AND AUGUST

27–30°C

Best for the warmest water and summer concerts

High summer brings the warmest sea of the year, usually 24–26°C and sometimes more near the shore on still days, and warm nights that keep the squares busy until late. Holidaymakers fill the beaches of Portorož, the Piran Musical Evenings bring chamber music to the monastery cloister, and berths and restaurant tables need booking ahead. Summer thunderstorms can bring short, sharp squalls, so the crew keeps an eye on the afternoon sky as well as the forecast.

SEPTEMBER

22–25°C

Best for warm water and a quieter coast

The sea holds on to much of its summer warmth, at around 22–23°C, while the beaches empty once schools go back. The salt harvest winds down by the middle of the month, the grape harvest begins in the vineyards behind Koper, and the maestral still fills in on many afternoons. Towards the end of the month, the first autumn spells of bora and jugo grow more likely.

OCTOBER

17–21°C

Best for the Barcolana and autumn food

The water cools to around 18–19°C, still fine for a brief swim on a sunny day, and the light over the gulf turns soft. On the second Sunday of the month, the Barcolana regatta fills the Gulf of Trieste with sails: in 2018 it entered the record books as the largest sailing race in the world, with 2,689 boats. Calm, clear days alternate with spells of bora and jugo, the olive harvest begins, and white truffles appear on the menus.