Best Time for a Blue Cave Tour from Kotor: Month, Sea Conditions & Time of Day

June: warm water and a calm sea

By June the sea off the Luštica coast has warmed to about 23°C, which most people find comfortable for a half-hour swim. In the wave model we checked, waves of 1 m or more reached the cave on fewer than 2% of June days, the lowest share of any month. Average highs are around 28°C, and rain falls on about five days in an average June. The town is busy but not yet at its peak: Kotor’s hotels had about 16,800 arrivals in June 2025, against 19,300 in August.

July and August: the warmest sea and the hottest days

The sea is at its warmest, about 25°C in July and 26°C in August, and July is the driest month of the year. The trade-off is heat on an open boat, with average highs above 31°C in July and about 32°C in August, and the busiest weeks in town. Summer brings a northwesterly breeze on many afternoons, but rough seas at the cave are still uncommon. Take the first departure you can, bring a hat and plenty of water, and book a few days ahead.

September: warm water, milder afternoons

The sea holds much of its summer warmth, at about 24°C, while average highs drop to about 27°C. Rain and rough seas become more common as the month goes on: rain falls on about seven days in an average September against five in June, and waves reached 1 m on about one September day in seven in the wave model. September is still busy in Kotor, with many cruise ship calls.

May and October: quieter, with a cooler sea

May is noticeably quieter in Kotor than the summer months, and regular departures have started, but the sea is only about 19°C, which many people find bracing. October keeps the sea at about 21°C and brings more rain and rough days; the town’s hotels are quieter than in September, although the port stays busy with cruise ships. Departures often thin out toward the end of the season, so check your date.

November to April: private trips only

Departures are much more limited in these months, and many are private, arranged on request or dependent on the weather. Some tours start in April or continue into November. The sea is about 14 to 16°C, rain is frequent, and waves of 1 m or more are common, especially in November. A winter trip is for the scenery of the bay and a quiet Kotor rather than for swimming.

Since May 2026, motorboats have been banned from entering the Blue Cave. Montenegro’s Ministry of Maritime Affairs announced the rule that month, and only craft without engines, such as kayaks, may go inside. Tours can still approach the cave, and on trips that include swimming, passengers may swim in when conditions allow. How that works on the day, including where the boat stops, depends on the boat and the sea.

This makes the sea on the day matter more than it used to. A swim in open water is only comfortable when the waves are small, and the cave faces the open Adriatic on the Luštica coast rather than the sheltered inner bay. It also makes water temperature part of the choice of month: a swim in 19°C water in May is a different experience from one in 25°C water in July.

If you would rather not swim, most Blue Cave tours from Kotor also take in the bay itself, and many include Our Lady of the Rocks, where the church museum usually charges a small cash entry fee that is not included in the tour price.

The cave gets its color from sunlight entering the chamber and reflecting off the water and the pale floor. The strongest blue light tends to appear from mid-morning toward midday on clear days, depending on the sun angle, and published advice varies: the Herceg Novi tourist organization says the effect is best on sunny days, especially before noon, while other guides suggest about 11am to 2pm. A cloudy sky dims the cave at any hour.

For practical reasons, a morning departure is usually the better booking. Sea conditions are often calmer, there are usually fewer boats around the cave, and in July and August the boat is cooler, which matters on a three-hour trip with little shade. A late-morning boat can reach the cave closer to midday, when the light is often strongest.

Morning departures are popular, so book them a few days ahead in summer. Later tours still reach the cave, usually in softer light and sometimes in choppier water.

Weather. Montenegro’s national weather service (ZHMS) publishes no climate normals for Kotor or Tivat. Temperatures, rainfall and rain days come from the 1991–2020 normals for the Herceg Novi weather station (WMO 13455), which ZHMS supplied to the World Meteorological Organization and NOAA archives. Herceg Novi sits at the mouth of the same bay, about 10 km from the Blue Cave. We cross-checked against the ERA5 reanalysis, which runs about 2°C cooler on summer highs, and did not publish it.

Sea. Sea temperatures are NOAA OISST 1991–2020 monthly averages for the satellite grid cell off Luštica. Wave figures are our own averages of the Open-Meteo marine model’s daily highest wave, 2022–2025, at the same point. Daylight is computed for Kotor on the 15th of each month.

Tours and the cave. The season is a summary of Kotor operators’ own websites and published visitor guides, checked on September 16, 2026: most run a regular season from roughly May to October, some start in April or continue into November, and winter trips are limited, often private or on request. The cave rule comes from the Ministry of Maritime Affairs’ announcement, reported by RTCG on May 25, 2026. The time-of-day advice comes from the Herceg Novi tourist organization and published visitor guides. Prices, ratings and review counts come from GetYourGuide on September 16, 2026.

Crowds. Hotel arrivals are MONSTAT’s monthly series for Kotor municipality (2025). Cruise calls are counted from the Port of Kotor’s 2026 schedule file. Festival dates come from the Municipality of Kotor’s 2026 events program and local reports.

What these numbers cannot tell you

• Climate normals are 30-year averages, not a forecast for your trip, and Herceg Novi is not Kotor: the old town sits deeper in the bay under steep mountains.
• The wave figures come from a model, not from buoys, and they do not count cancelled tours. None of the operators we checked publishes a cancellation rate or a single wind or wave limit that all boats use.
• Hotel arrivals are a proxy for how busy Kotor is. They do not count private apartments, day visitors or cruise passengers, and nothing here measures how many people are at the cave.
• Operators publish different seasons, and not all publish one. The booking calendar on this page shows what is actually available for your date.
• The booking calendar lets you pick almost any date; that is not proof a shared boat is running on it, especially from November to April.
• We do not have per-date prices, so this page does not name a cheapest month.