Can I only buy it in season?
It is listed as Main season April–August. It is harvested all year, but quantity and price can change with the season and the variety. The calendar does not guarantee that the fruit is on sale on any given day.
Durian · ทุเรียน
If its strong smell has made you hesitate, you can still try just a little durian. Inside the spiny husk is rich yellow flesh. It is a fruit where you take a bite of soft, sweet flesh and notice the aroma and taste together. If it is your first time, start at a seller that offers a small amount of flesh rather than buying a whole fruit.

Main season April–August
Listed as harvested all year
Sisaket volcanic soil durian: harvest listed May–June
Use the main season, or the harvest period of a regional fruit, as a guide. Actual harvests can vary with the growing area, the variety and the weather.
Its features are a sweet, rich taste and creamy flesh. The firmness and aroma of the flesh vary with the variety, such as Monthong and Chanee, and with how ripe it is.
Thai durian varieties such as Monthong, Chanee and Kan Yao are well known. Its strong smell and sweet, rich flesh make it a fruit that people feel very differently about. You can eat it as fruit or enjoy it in ice cream and desserts.
It is listed as Main season April–August. It is harvested all year, but quantity and price can change with the season and the variety. The calendar does not guarantee that the fruit is on sale on any given day.
First ask whether the price is per kg of whole fruit including the husk or per kg of prepared flesh. If you want to take it to a hotel or onto transport, check the rules on bringing it in first.
If you want to read more about the food and the regions behind it, these sources are a good next step. Ingredients and cooking methods can differ from one place to the next.
Sharing image credit: مانفی · CC BY-SA 4.0