With fewer pieces of fruit per tree, Spain’s Lemon and Grapefruit Interprofessional Association (Ailimpo) expects the total grapefruit harvest to be down by almost a quarter on last season.
In a release, the group said the harvest would likely sit at around 61,000 metric tons (MT), but fruit sizing would be up.
"The production area remains stable, and the decreased crop is due to irregular flowering, which affected production variably," the association said.
"The reduction in harvest is more marked in older fields, while the production estimates for younger fields are similar to last season's."
Despite the overall decrease, Ailimpo said expectations for the sector were good given the Spanish grapefruit winter season was confirmed as having the second-greatest volume in Europe after Turkey.
"However, regarding product quality, Spanish grapefruit is a distinctly better quality than Turkish grapefruit, which gives us a clear potential for growth," the association said.
"Moreover, given the decrease in supply from Florida and Israel, Spanish grapefruit has clearly become a leading and essential source in the EU for meeting demand."
In the 2016-17 season the majority of Spanish grapefruit was sent to Germany and France, representing 50% of total sales at 31,000MT.
A small amount of 2,500MT was also exported to overseas countries, but this was a sharp increase amid 'outstanding efforts' to open and strengthen markets such as Switzerland, South Africa, China, Saudi Arabia and the United Arab Emirates.
"The domestic market was estimated at 7,000 tonnes, with a slight year-on-year increase and a greater presence of grapefruit in supermarkets and fruit vendors," Ailimpo said.
"The industry also processed 10,000 tonnes, absorbing the lowest-quality fruit."