Palm Oil recorded its biggest weekly gain in three years and send futures into a bull market, as it advanced on speculation that rain may have diminished production in main suppliers Indonesia and Malaysia.

Futures climbed 1.2 percent to 2,623 ringgit ($827) a metric ton on the Bursa Malaysia Derivatives, the highest close since September 2012. The new value marks a 21 percent increase over the 2,167 ringgit settlement on July 29, meeting the common definition of a bull market. Palm gained 7.3 percent this week, the most since 2010, and is set for its first annual gain in three years.

Prices hiked up on fears that output is less than analysts expected and that beginning of the monsoon season this month would further restrict supply. Although palm enjoys year-=long production, output peaks from July to October. Several major plantations in Indonesia said production unexpectedly fell 7 to 10 percent in the first 10 months due to rain and the growing cycle.

With stockpiles lower than last year’s and third-quarter production, the most significant one in the year, also lagging in comparison investors seem to have gown excited over the commodity.