The International Center for Research on the El Niño Phenomenon (CIIFEN) has published a new edition of the Agroclimatic Bulletin for Blueberry Growers in Peru, developed exclusively for Blueberries News with the aim of providing relevant climate information for the country’s main production regions.
The document analyzes the conditions observed during May 2026 and presents precipitation and temperature outlooks for June, July, and August, as well as an assessment of agroclimatic variables of interest for the crop, such as the accumulation of Growing Degree Days (GDD).
According to the report, above-average maximum and minimum temperatures were recorded during May across much of Peru’s coastal and highland regions. This situation occurred in a context of positive sea surface temperature anomalies off the Peruvian coast and under the influence of warm conditions in the equatorial Pacific.
Ocean-atmosphere context
The bulletin indicates that positive sea surface temperature anomalies continued to be recorded in the Niño 1+2 region off the coast of Peru, a condition associated with the current Coastal El Niño scenario.
According to information compiled by CIIFEN, the Multisectoral Commission in charge of the National Study of the El Niño Phenomenon (ENFEN) maintains its alert status for this phenomenon and considers its persistence until February 2027 to be the most likely scenario, with a possible moderate intensity and peak development between July and September.
At the same time, projections indicate a transition toward warm conditions in the central Pacific beginning in June. The bulletin also includes estimates from international organizations indicating a high probability of an El Niño event developing during the second half of 2026.
The World Meteorological Organization (WMO), cited in the report, indicated in early June that there was an approximately 80% probability that El Niño conditions would become established between June and August, with this percentage expected to increase in the following months.
According to the document, the evolution of both phenomena represents one of the main factors requiring close monitoring for agricultural activities during the 2026–2027 season.
Rainfall behavior during May
In general terms, the rainfall observed during May was consistent with the transition toward the dry season across much of Peru’s blueberry-producing regions.
On the northern coast, rainfall anomalies were close to -2 mm compared with the historical average. The central and southern coasts, meanwhile, recorded virtually no accumulated rainfall, a condition considered normal for this time of year.
In the highlands, differences were observed between regions. The largest deficits were recorded in the Northwestern Highlands and Northeastern Highlands, with anomalies of -29 mm and -23 mm, respectively.
On the other hand, some areas recorded rainfall above climatological values. Among these were the Eastern Central Highlands, with an anomaly of +6 mm, and the Southeastern Highlands, with +11 mm.
According to CIIFEN’s analysis, these results reflect the gradual end of the rainy season and the establishment of drier conditions across most production regions.
Temperatures above historical averages
The main signal identified by the bulletin relates to temperature behavior.
During May, coastal regions recorded maximum and minimum temperatures above normal values. The largest anomalies were observed along the northern and central coasts, where both maximum and minimum temperatures exceeded historical averages by more than 2°C.
On the northern coast, maximum temperatures ranged between 28 and 30°C, while minimum temperatures fluctuated between 18 and 20°C. On the central coast, maximum temperatures ranged from 24 to 26°C and minimum temperatures from 16 to 18°C. The southern coast showed similar conditions, with maximum temperatures between 25 and 27°C and minimum temperatures between 15 and 17°C.
Above-normal temperatures were also recorded in the highlands, although anomalies were smaller than those observed along the coast.
The report attributes this behavior primarily to the persistent warming of the ocean off the Peruvian coastline, a condition that has remained in place throughout much of the year.
Outlook for June, July, and August
For the June–July–August period, the bulletin projects a continuation of the seasonal dry conditions across most blueberry-producing regions.
On the northern coast, rainfall is expected to remain within the normal range for the season, while the central and southern coasts are likely to maintain very low or near-zero accumulations. A similar situation is projected for many of the western highlands.
The exception is expected in parts of the Eastern Central Highlands, where there is a higher probability of above-normal rainfall during June and July, extending the pattern observed during May.
As for temperatures, forecasts indicate a higher probability of above-normal values across both coastal and highland regions.
The bulletin notes that these conditions could persist throughout the entire quarter and that positive temperature anomalies may intensify along the northern and central coasts during July and August, coinciding with the period when the Coastal El Niño is expected to reach its peak development.
What the Growing Degree Days indicate
One of the indicators incorporated into this edition of the bulletin is Growing Degree Days (GDD), a tool used to estimate the accumulation of heat available for plant growth and development.
GDD are calculated using a base temperature of 10°C, the threshold above which blueberry plants begin active development. Their accumulation makes it possible to estimate the progression of different phenological stages and compare the performance of a season against historical values.
The results show that all analyzed regions recorded accumulations above historical averages as of May 31, 2026.
The Northern Coast accumulated 2,577 GDD, with a positive anomaly of +143. The Central Coast recorded 2,085 GDD (+162), while the Southern Coast reached 2,088 GDD (+162).
In the highlands, the largest differences were observed in the Southwestern Highlands, with an anomaly of +170 GDD, followed by the Eastern Central Highlands, with +105 GDD.
According to CIIFEN, the temperatures projected for June, July, and August could continue to favor above-average heat accumulation across all production regions.
Temperatures and floral induction
As part of the agroclimatic analysis, the bulletin devotes a specific section to the relationship between projected temperatures and blueberry floral induction.
The document notes that this process requires temperatures below 20°C for proper development and points out that the thermal conditions forecast for the coming months make it advisable to maintain close monitoring of this variable.
According to the report, maximum and minimum temperatures have remained above normal values since February, and forecasts indicate that this condition is likely to continue throughout the winter.
CIIFEN recommends paying particular attention to nighttime temperatures and evaluating the conditions observed at each farm according to the crop’s phenological stage and the characteristics of each production region.
Looking ahead to the 2026–2027 season
In addition to the outlook for the June–July–August period, the bulletin includes an assessment of possible scenarios for the following months.
According to the document, the probability of above-normal rainfall could increase during September and October in parts of the northern coast and the highlands, coinciding with the onset of the rainy season and a possible intensification of warm conditions in the Pacific.
Later, between November 2026 and February 2027 — the period during which international agencies project the peak intensity of the El Niño phenomenon — the report recommends paying particular attention to variables related to drainage, soil management, plant health, and phytosanitary monitoring.
The bulletin also notes that higher temperatures could favor increased pest activity and raise the risk of certain diseases, recommending that field monitoring programs be strengthened accordingly.
Finally, CIIFEN reminds readers that seasonal forecasts represent probabilistic trends and should not be interpreted as predictions of specific extreme events. Nevertheless, they constitute a valuable tool to support planning and decision-making throughout the different stages of crop production.
