Haïti, climat et météo mensuels, août 2025

FAMINE EARLY WARNING SYSTEMS NETWORK Haiti Monthly Climate and Weather 18 September 2025 Highlights • During August 2025, ENSO-neutral conditions continued, with near average sea surface temperatures (SSTs) registered across the central and eastern equatorial Pacific Ocea. According to the NOAA ENSO Diagnostic Discussion, a transition from ENSO-neutral to La Niña is likely in the next couple of months, with a 71% chance of La Niña during October - December 2025. Historically, El Niño is associated with drier than average conditions and La Niña with wetter than average conditions in Haiti. • August is the first month of the second rainy season in Haiti. Climatological rainfall ranges from 25 mm to 300 mm across Haiti. • During August 2025, Haiti’s central departments observed rainfall values between 25 mm to 50 mm, while the rest of Haiti’s departments registered values ranging from 5 mm to 25 mm. Drier than average conditions continued over Haiti. • The MME seasonal forecast for October – December 2025 suggests enhanced probabilities exceeding 40% for above normal in southern Haiti, while forecast probabilities for above normal rainfall are less than 40% in northern Haiti. No dominant tercile category is forecasted for the rest of the country. The SPI forecast suggests above-average conditions in northwestern, central-eastern, and southeastern Haiti, while drier than average conditions are indicated in Grande-Anse department. 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 • During August 2025, ENSO-neutral conditions continued, with near average sea surface temperatures (SSTs) observed across the central and eastern equatorial Pacific Ocean. According to the NOAA ENSO Diagnostic Discussion, a transition from ENSO-neutral to La Niña is likely to occur in the next couple of months, with a 71% chance of La Niña during October - December 2025. Thereafter, La Niña is favored but chances decrease to 54% in December 2025 - February 2026 (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 11 September 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 September to November 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 last month, a lack of rainfall, soil moisture deficits, and stressed vegetation conditions have led to the continuation of abnormal dryness in Haiti. • There have been no reports of fire activity in Haiti during August 2025. Rainfall/Precipitation • August is the first 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 (June – August2025): • Totals: Over the last three months, the largest amounts of total rainfall ranged from 50 mm to 150 mm in central Haiti and in a few areas in the southwest. The rest of the country received rainfall totals of 10 mm – 50 mm. • Anomalies: During the last three months, Haiti experienced below average conditions over the country. Central Haiti’s departments, Nord department and northern Ouest department registered the highest rainfall deficits ranging from 200 mm to more than 500 mm, while the rest of Haiti registered below average amounts from 25 mm to 200 mm. Past 1 Month (August2025): • Totals: During the past month, Haiti’s central departments observed rainfall values between 25 mm to 50 mm, while the rest of Haiti’s departments registered values raging from 5mm to 25 mm (Fig. 2a). • Anomalies: During August, drier than average conditions continued over Haiti. Central Haiti’s departments registered the highest rainfall deficits ranging from 100 mm to 300 mm, while the rest of Haiti registered below average conditions from 25 mm to 100 mm (Fig. 2b). 3 a) b) c) Figure 2. Satellite estimates of precipitation (CMORPH) for August 2025: (a) 1-month total accumulation and (b) 1-month anomaly. (c) NMME seasonal rainfall probabilistic forecast for October – December 2025. Source: NOAA/NCEP Monthly and Seasonal Forecasts (October 2025 and October – December 2025): • Monthly: The North American Multi-Model Ensemble (NMME) models indicate no clear signal for near-, above-, or below-average rainfall conditions during October 2025. • Seasonal: The NMME seasonal forecast for October – December 2025 suggests probabilities for above average rainfall exceed 40% in southern Haiti, while forecast probabilities for above average are between 36% and 40% in northern Haiti. The rest of the country indicates no clear signal for near-, above-, or below-average rainfall conditions (Fig. 2c). Temperature Past 3 months (June – August 2025): • Maximums: Haiti experienced maximum temperatures ranging from 30°C to 35°C. Northwestern, western, and southern departments experienced slightly above average anomalies between 1°C and 2°C, while the rest of Haiti observed near average temperature anomalies. • Minimums: Most of Haiti recorded minimums between 20°C and 25°C. Cooler temperatures of 15 °C – 20 °C were observed in southeastern Haiti while warmer temperatures of 25 °C – 30 °C were recorded in northwestern Haiti. Near average minimum temperature anomalies prevailed in Haiti during August, except for areas of southwestern Haiti that recorded above average anomalies between 1°C and 2°C. Past 1 Month (August 2025): • Maximums: Monthly Maximum temperatures ranged from 30°C to 40°C in Haiti. Above average anomalies between 2°C and 3°C were observed in southwestern departments, while the rest of country registered slightly warmer anomalies of 1-2 °C (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 4 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). a) b) c) Figure 3. Spatial structure of temperature for August 2025. (a) Maximum temperature anomaly and (b) minimum temperature anomaly. (c) NMME probabilistic forecast of seasonal 2-m temperature for October – December 2025. Source: NOAA/NCEP Monthly and Seasonal Forecasts (October 2025 and October – December 2025): • Monthly: The NMME forecast indicates no clear dominant signal for either below or above average temperatures in Haiti during October. • Seasonal: For the October – December 2025 season, there is an increased likelihood (over 60%) of above average temperatures in northern, western, and southern regions of Haiti. The forecast indicates no clear signal for near-, above-, or below-average 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 takes evapotranspiration into account (and therefore the impact of temperatures on water demand). Past 3 Months (June – August 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. 5 Past 1 Month (August 2025): • The SPI analysis for August 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 western Artibonite department. Current/Forecast (1 July 2025 to 28 September 2025): • The SPI forecast suggests near average SPI conditions for most of the country. However, SPI forecast seems to indicate drier-than-average conditions (SPI values ranging from 0.8 to -1.3 standard deviations below the mean) in Grande-Anse department. On contrast, the forecast suggests wetter-than-average conditions (SPI values ranging from 0.5 to 0.8 standard deviations above the mean) in northwestern, central-eastern, and southeastern Haiti. Water Requirement Satisfaction Index (WRSI) • USGS/EROS crop WRSI: Current conditions during the 3rd Dekad of August 2025 depicted ‘Average’ to ‘Good’ crop conditions in most of Haiti. However, areas in Nord-Ouest, northern Nord-Est, and northern Ouest departments depicted ‘Failure’ to ‘Poor’ crops conditions. GEOGLAM Crop Monitor • GEOGLAM Crop Monitor synthesis indicated that ‘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 September-October-November (SON) 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