Can I only buy it in season?
It is listed as Main harvest Oct–Dec. 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.
Pomelo · ส้มโอ
Try a pomelo, which looks like a giant grapefruit. Peel the thick rind and remove the membrane, and the granules of flesh appear. Sweetness and tartness feel different depending on the variety. If using a knife at your lodging is hard, you can choose prepared pomelo sold in a pack.

Main harvest Oct–Dec
Listed as available year-round
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.
It is a citrus fruit where you feel the granules of flesh. The color and the sweetness and tartness differ by variety, with flesh that is yellowish or pinkish.
Thailand has several pomelo varieties, such as khao nam phueng and thong dee. Large whole fruit is sometimes prepared and sold as flesh only, which makes it an easy fruit to try while traveling.
It is listed as Main harvest Oct–Dec. 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.
Tell apart the price per fruit, the price per kilogram and the price of a prepared pack. Whole fruit with its rind and a pack of flesh only are hard to compare directly by the same weight.
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: Ivar Leidus · CC BY-SA 4.0