Can I only buy it in season?
It is listed as Main harvest Apr–Aug. It is a year-round fruit, but volume and price can change with the season and variety. The calendar does not guarantee that it is on sale on any given day.
Durian · ทุเรียน
If its strong smell has made you hesitate, try just a little durian. Inside the spiky husk is rich yellow flesh. It is a fruit where you taste the aroma and the soft, sweet flesh together. If it is your first time, start with a small portion of flesh from a seller rather than buying a whole fruit.

Main harvest Apr–Aug
Listed as available year-round
Sisaket volcanic-soil durian: harvest listed for May–Jun
Use the main harvest period, or the harvest window for a regional fruit, as a guide. Actual availability can change with growing region, variety and weather.
Its traits are a sweet, rich taste and creamy flesh. How firm the flesh is and how strong the smell is vary with the variety, such as monthong and chanee, and with ripeness.
Thai durian varieties such as monthong, chanee and kan yao are well known. It is also a fruit people feel strongly about because of its strong smell and sweet, rich flesh. You can eat it as it is or enjoy it as ice cream and desserts.
It is listed as Main harvest Apr–Aug. It is a year-round fruit, but volume and price can change with the season and variety. The calendar does not guarantee that it is on sale on any given day.
Ask first whether the price tag is per kilogram of whole fruit with the husk or per kilogram of prepared flesh. If you want to take it to a hotel or onto transportation, 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 place to start. Ingredients and recipes can vary from one restaurant to the next.
Sharing image credit: مانفی · CC BY-SA 4.0