Haiti Monthly Climate and Weather, September 2025

FAMINE EARLY WARNING SYSTEMS NETWORK Haiti Monthly Climate and Weather 16 October 2025 Highlights • La Niña conditions emerged in September 2025, as indicated by the expansion of belowaverage sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean. The ENSO outlooks anticipate La Niña conditions are favored to persist through December 2025 - February 2026, with a transition to ENSO-neutral likely in January-March 2026 (55% chance). Historically, El Niño is associated with drier than average conditions and La Niña with wetter than average conditions in Haiti during October-December. • September is the second month of the second rainy season in Haiti. Climatological rainfall ranges from 25 mm to 300 mm across Haiti. • During September 2025, rainfall was above average in northwestern and Southwestern Haiti. FEWS NET indicated that theses rainfall events supported the second-season planting particularly in the northern Haiti. Haiti’s Grand’Anse, Nippes, Sud departments and Gonave Island observed rainfall values between 100 mm to 300 mm, while the rest of Haiti’s departments registered values ranging from 10 mm to 100 mm. During the month, drier than average conditions continued over eastern and central Haiti, whereas Nord-Ouest, parts of southwestern Haiti and Gonave Island experienced above average conditions. • The NMME seasonal forecast for November 2025 – January 2026 suggests enhanced probabilities exceeding 40% for above normal over most parts of Haiti • The SPI forecast suggests above-average conditions in northwestern, northern, and southeastern Haiti. Near-average conditions are expected for the rest of the country. The FEWS NET Monthly Climate and Weather information bulletin is based on current weather and climate information and monthly and seasonal outlooks from the NOAA CPC. Information on crops, soil moisture, flooding, and evapotranspiration data were produced by FEWS NET, USGS, NASA and USDA. Various sources were used to assess impacts of extreme conditions. Questions or comments about this product may be directed to Dr. Wassila Thiaw, Deputy Director, CPC/NOAA, wassila.thiaw@noaa.gov. Questions about the DOS FEWS NET may be directed to Dr. Kiersten Johnson, Program Manager FEWS NET/DOS, johnsonkb2@state.gov. Haiti seasonal calendar. Source: FEWS NET Current Climate Modes and Teleconnections • In September 2025, La Niña conditions emerged, as indicated by the expansion of belowaverage sea surface temperatures (SSTs) across the central and eastern equatorial Pacific Ocean. Over the western and east-central equatorial Pacific, low-level wind anomalies were easterly and upper-level wind anomalies were westerly. Convection continued to be enhanced over Indonesia and was suppressed near the Date Line. The equatorial Southern Oscillation index was positive. Collectively, the coupled oceanatmosphere system reflected La Niña conditions. • The ENSO outlooks predict La Niña conditions are favored to persist through December 2025 - February 2026, with a transition to ENSO-neutral likely in January-March 2026 (55% chance; Fig. 1). For the latest update from the NOAA Climate Prediction Center (CPC) on ENSO, check here. • Much of the Caribbean Sea experienced positive SST anomalies of 0.5 – 1°C. Figure 1. Official ENSO probabilities for the Niño 3.4 SST index (5oN−5oS, 120oW−170oW). Figure updated 9 October 2025. Source: NOAA/CPC 2 • Implications of ENSO conditions: Based on historical records, La Niña conditions are associated with above average precipitation throughout Haiti for October to December season (Fig. A1, left panels). La Niña conditions are also related to below average mean temperatures in Haiti (Fig. A1, right panels). The ENSO-precipitation teleconnection pattern can be found here, and the pattern for temperature can be found here Extreme Events • During the night of September 16–17, heavy rainfall caused the Trois-Rivières River to overflow, leading to extensive inundation across several neighborhoods in Port-de-Paix and Bassin-Bleu (OCHA, 24 September 2025). • Casualties and displacement: The inundation resulted in one confirmed death, one injury, and several people missing. At least 823 families were affected, and over 650 homes were flooded or destroyed (OCHA, 29 September 2025). • Widespread damage: The floods caused significant damage to houses, schools, and crops. Important infrastructure was impacted, including the Trois-Rivières bridge, and several roads were cut off (OCHA, 2 October 2025). • There have been no reports of fire activity in Haiti during August 2025. Rainfall/Precipitation • September is the second month of the second rainy season in Haiti. Climatological rainfall ranges from 25 mm to 300 mm across Haiti. The highest rainfall totals are observed in central Haiti (200-300 mm); lower rainfall amounts (25-75 mm) are climatologically expected in northern and southern Haiti. Past 3 months (July – September 2025): • Totals: Over the last three months, the largest amounts of total rainfall ranged from 200 mm to 300 mm in southwestern Haiti and Gonave island. The Centre and Artibonite department of Haiti’s experienced moderate rainfall, with totals of 100 mm to 200 mm. The Nord, Nord-Est, most parts of Nord-Ouest, Sud-Est, southern Ouest received comparatively lower amounts of rainfall, ranging from 25 mm to 100. • Anomalies: During the last three months, Haiti experienced below average conditions over most of the country, whereas few parts of southwestern Haiti experienced above average conditions. Parts of Centre department, and parts of Artibonite registered the highest rainfall deficits ranging from 300 mm to 500 mm, while the rest of Haiti registered below average amounts from 25 mm to 200 mm. Past 1 Month (September 2025): • Totals: During the past month, Haiti’s Grand’Anse, Nippes, Sud departments and Gonave Island observed rainfall values between 100 mm to 300 mm, while the rest of Haiti’s departments registered values ranging from 10 mm to 100 mm (Fig. 2a). 3 • Anomalies: During September, drier than average conditions continued over eastern and central Haiti, whereas Nord-Ouest, parts of southwestern Haiti and Gonave Island experienced above average conditions. Central, Artibonite, Nord, Nord-Est, Ouest, and Sud-Est departments registered the highest rainfall deficits ranging from 100 mm to 200 mm. In contrast, the Grand’Anse, Sud, Nippes, and Nord-Ouest departments registered above-average rainfall between 25 mm to 100 mm. Similarly, western parts of Gonave Island, central Sud, western Nippes recorded above average rainfall from 25 mm to 100 mm. (Fig. 2b). b) a) c) Figure 2. Satellite estimates of precipitation (CMORPH) for September 2025: (a) 1-month total accumulation and (b) 1-month anomaly. (c) NMME seasonal rainfall probabilistic forecast for November 2025 – January 2026. Source: NOAA/NCEP Monthly and Seasonal Forecasts (November 2025 and November 2025 – January 2026): • Monthly: The North American Multi-Model Ensemble (NMME) models indicate above- normal rainfall over Central Haiti’s Department during November 2025. • Seasonal: The NMME seasonal forecast for November 2025 – January 2026 suggests probabilities for above average rainfall exceed 36% over most parts of Haiti. (Fig. 2c). Temperature Past 3 months (July – September 2025): • Maximums: Haiti experienced maximum temperatures ranging from 30°C to 35°C. Most of the departments experienced slightly above average anomalies between 1°C and 2°C, while northeastern Haiti observed near average temperature anomalies. • Minimums: Most of Haiti recorded minimums between 15°C and 25°C. Cooler temperatures of 15°C – 20°C were observed in southeastern Haiti while warmer temperatures of 20°C – 25°C were recorded in southwestern and central and northern Haiti. Near average minimum temperature anomalies prevailed in Haiti during September. 4 Past 1 Month (September 2025): • Maximums: Monthly maximum temperatures ranged from 35°C to 40°C in Haiti. Above average anomalies between 1°C and 2°C were observed in northern, central and southwestern departments, while the southeastern regions registered near-average anomalies (Fig. 3a). • Minimums: Most of Haiti recorded minimum temperatures between 20°C and 25°C, but isolated areas in southeastern Haiti observed cooler minimums ranging from 15°C to 20°C, while the far northwestern Haiti observed warmer minimum temperatures of 2530°C. Compared to the long-term climate, the observed values were within ±1oC of the average across Haiti (Fig. 3b). b) a) c) Figure 3. Spatial structure of temperature for September 2025. (a) Maximum temperature anomaly and (b) minimum temperature anomaly. (c) NMME probabilistic forecast of seasonal 2m temperature for November 2025 – January 2026. Source: NOAA/NCEP Monthly and Seasonal Forecasts (November 2025 and November 2025 – January 2026): • Monthly: The NMME forecast indicates no clear dominant signal for either below or above average temperatures in Haiti during November. • Seasonal: For the November 2025 – January 2026 season, there is an increased likelihood (over 60%) of above average temperatures in northern, north-eastern, and southern regions of Haiti. The forecast indicates no clear signal for near-, above-, or belowaverage temperatures in the central-east regions of the country (Fig. 3c). Drought and Dryness The Standardized Precipitation Index (SPI) is used to characterize meteorological drought. SPI compares the precipitation over a specific period of time with the climatology from that same period. Therefore, the SPI values can be thought of as the number of standard deviations the observed anomaly deviates from the climatology. The 1-month SPI values are a good representation of the monthly precipitation anomaly as well as the soil moisture and vegetation health. The 3-month SPI values are a good representation of seasonal precipitation anomalies. The Standardized Precipitation Evapotranspiration Index (SPEI) is similar to the SPI, but it also 5 takes evapotranspiration into account (and therefore the impact of temperatures on water demand). Past 3 Months (July – September 2025): • The SPI analysis for the past 3 months indicated that drier than average conditions (SPI values of 0.8 to more than 2 standard deviations below the mean) dominated over Haiti. The highest deficits (more than 2 standard deviations below the mean) were experienced in Nord-Ouest, Artibonite, and northern Nord departments. Past 1 Month (September 2025): • The SPI analysis for September 2025 indicated that Haiti experienced drier than average conditions (SPI values of 0.8 to more 2 standard deviations below the mean) across the country. The highest deficits (more than 2 standard deviations below the mean) were experienced in eastern Artibonite and western Centre department. Current/Forecast (1 October 2025 to 28 October 2025): • The SPI forecast suggests near average SPI conditions for most of the country. However, SPI forecast seems to indicate wetter-than-average conditions (SPI values ranging from 0.5 to 1.3 standard deviations above the mean) in Nord-Ouest, northern Nord, northern Nord-Est, western Artibonite, Grand’Anse, Sud, Nippes, and eastern parts of Sud-Est department. Water Requirement Satisfaction Index (WRSI) • USGS/EROS crop WRSI: Current conditions during the 3rd Dekad of September 2025 depicted ‘Average’ to ‘Good’ crop conditions in most of Haiti. However, northern NordOuest, northern Nord-Est, central Ouest departments depicted ‘Failure’ to ‘Poor’ crops conditions. GEOGLAM Crop Monitor • GEOGLAM Crop Monitor synthesis indicated ‘favorable’ conditions in Haiti for maize and rice during September 2025. Additional Resources - https://protectioncivile.gouv.ht/ - https://www.meteo-haiti.gouv.ht/ 6 Annex Figure A1. ENSO teleconnection for the October-November-December (OND) season. The upper-level panel shows the precipitation and temperature anomalies regressed onto the standardized Niño-3.4 index. The bottom panel shows the correlation between Nino-3.4 and the anomalies. Source : https://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/regressions/ 7