In short, January through to September are the best months for diving in Koh Tao. But here’s a more in depth overview of how the weather affects SCUBA throughout the year. Koh Tao is a year-round diving destination, offering excellent underwater conditions for most of the year. However, if you’re looking for the absolute best diving conditions, the period from January to September offers the most stable visibility, warm water temperatures, and comfortable surface conditions. Diving Conditions from January to September The first nine months of the year provide optimal diving conditions, with calm seas, great visibility, and minimal weather disruptions. This period is ideal for divers of all levels, whether you’re getting your Open Water certification or looking to explore deeper sites. February to May – The Absolute Calmest Diving Months If you’re looking for the calmest conditions, then February through May is the prime diving season in Koh Tao. During these months, the sea is at its flattest, making boat rides to dive sites smooth and surface conditions perfect for snorkeling and free diving. Additionally, if spotting a whale shark is on your bucket list, then March and April are the best months for sightings. These gentle giants are known to frequent the waters around Koh Tao during this time, making for unforgettable diving encounters. June to September – Possible Windy Conditions Starting in June, Koh Tao can experience some wind due to the west coast monsoon affecting Thailand’s Andaman Sea. This wind can last between one to three months, but it rarely disrupts diving conditions around Koh Tao. Instead, it primarily affects the surface conditions, causing choppier boat rides to dive sites. Underwater, the diving remains fantastic, with good visibility and an abundance of marine life. The Monsoon Season – November to January Koh Tao’s monsoon season usually arrives in late November, bringing heavier rains and occasional storms. While diving is rarely canceled entirely, the month of December and sometimes into January can be particularly wet. How Does the Monsoon Affect Diving? Increased rainfall can create run-off from the land, introducing extra nitrogen into the water. Excess nitrogen can trigger algae blooms, which, while beautiful, can reduce visibility underwater. While surface conditions can be rougher than usual, diving is still possible most days. That being said, even during monsoon season, there are many calm and clear diving days—so if you’re visiting during this time, you can still enjoy incredible dives. Summary: The Best Time to Dive in Koh Tao Best Overall Diving Months: January – September Calmest Conditions: February – May Best for Whale Sharks: March – April Potentially Windy (but good underwater conditions): June – September Rainiest Months (but still diveable): November – January Ready to Dive in Koh Tao?No matter when you visit, diving in Koh Tao is an incredible experience! Whether you’re here for the crystal-clear waters of the dry season or the marine-rich waters of monsoon season, there’s always something magical to see underwater. Book your dive course with Phoenix Divers Koh Tao today and experience the best diving Thailand has to offer!Get in touch