Arabfields, Maleeka Kassou, East, West and Central Africa Agriculture Correspondent — Heavy rainfall during critical stages of cocoa development is emerging as a major threat to Ghana’s harvest, raising concerns about farmers’ incomes, export earnings and the stability of global chocolate supplies.

New research published in September in the journal Proceedings of the National Academy of Sciences found that excessive wet-season rainfall and dry-season drought together explain about 68% of year-to-year variations in Ghana’s cocoa production. The findings challenge the assumption that higher temperatures and insufficient rainfall are the main weather-related risks facing cocoa growers.

The research comes as Ghana’s cocoa industry confronts another difficult production outlook. The country’s cocoa regulator, COCOBOD, has forecast that output could fall by at least 16% in the 2026/27 season, citing excessive rainfall earlier in the year, the possibility of El Niño conditions, crop-cycle fluctuations and disease.

For farmers, the consequences can be felt months before harvesting begins. Cocoa trees are particularly vulnerable during flowering and the early development of young pods, when intense rainfall and strong winds can damage delicate plant structures and reduce the number of pods that survive to maturity.

“Rainfall is variable and farmers are not able to predict what the pattern could be in the following years,” said Eric Opoku Mensah, a research scientist at Ghana’s Plant Genetic Resources Research Institute, describing the difficulties producers face when planning farm operations.

The timing of rainfall matters as much as the total amount received. Researchers found that heavy downpours during flowering can disrupt pollination, damage young pods and create favourable conditions for fungal infections, including black pod disease. These effects can reduce yields even when overall water availability appears adequate.

Ghana is the world’s second-largest cocoa producer, and its fortunes are closely linked to those of neighbouring Côte d’Ivoire. Together, the two countries account for approximately 60% of global cocoa production, giving weather-related disruptions in West Africa significant implications for international commodity markets.

The sector supports millions of livelihoods, from smallholder farmers and farm labourers to traders, transport operators and chocolate manufacturers. A weaker harvest can therefore affect household incomes and government export revenues while tightening supplies for buyers overseas.

The new study also found similar relationships between heavy rainfall and cocoa yields in Indonesia and Ecuador, suggesting that the problem extends beyond West Africa. The researchers’ findings indicate that extreme precipitation during sensitive growth stages may be a broader constraint on cocoa production across tropical regions.

Ghana’s agricultural challenges are compounded by rising temperatures and increasingly unpredictable weather. Average temperatures in cocoa-growing areas have risen from approximately 26 degrees Celsius in the 1960s to 1980s to around 27 to 28 degrees today, according to Mensah. Farmers must now manage the combined risks of heat, drought, excessive rainfall and crop disease.

The immediate outlook remains uncertain. If dry conditions develop during the coming months, young pods could face additional stress. Conversely, sustained but moderate rainfall could help replenish soil moisture and support pod development. The effect on the eventual harvest will depend on how weather conditions evolve during the remaining growing season.

Researchers say improved weather forecasting could help farmers prepare for periods of elevated risk. Seasonal forecasts and early-warning systems could allow growers to adjust farm activities, improve drainage and apply disease-control measures before conditions deteriorate.

Other adaptation options include planting more climate-resilient cocoa varieties, growing shade trees alongside cocoa and improving water management. Agroforestry could help protect trees against heat and strong winds, while water collected during wetter periods could be stored for use during dry spells.

However, these measures require investment, technical support and access to agricultural inputs. Smallholder farmers with limited financial resources may struggle to implement them without assistance from government agencies, cooperatives and development partners.

The outlook for Ghana’s 2026/27 crop will depend on both weather conditions and the effectiveness of measures to control disease and rehabilitate affected farms. If production declines as projected, pressure on cocoa supplies and export earnings could intensify. A recovery in rainfall patterns and improved farm management could limit some losses, although neither outcome is guaranteed.

For Ghana, the challenge is no longer simply to produce more cocoa, but to protect yields against increasingly difficult growing conditions. The research suggests that better anticipation of rainfall extremes could become an essential part of that effort, helping farmers make more informed decisions and reducing the risk of another damaging harvest season.