Recent changes (1940-2024) in temperature and precipitation in Togo using ERA5 and observational data.

Using ERA5 reanalysis data we produce a comprehensive analysis of the evolution of Togo’s Climate between 1940 and 2024. It reveals a robust and spatially widespread warming signal and a strong variability in precipitation. ERA5 results are compared with a set of observations provided by ANAMET.

Nationally averaged series show that mean temperature in Togo has risen by about 1.1 ºC in 2015–2024 relative to 1961–1990, with slightly stronger warming of around 1.2 ºC in the Maritime and Plateaux regions. Percentile‑based and absolute‑threshold indices reveal a sharp shift towards more frequent heat, as warm days and nights (TX90p, TN90p), summer days above 35 ºC (SU35) and tropical nights above 25 ºC (TR25) have all increased markedly, while cold days and nights (TX10p, TN10p) have become rare.

Rainfall in Togo exhibits pronounced interdecadal variability, with a notably wetter period from about 1965 to 2000 bounded by drier conditions. Recent conditions (2015-2024) are markedly drier relative to 1961–1990, with negative rainfall anomalies across all regions, with a national mean reduction of roughly 136 mm. Seasonal regimes also diverge, as monomodal areas (Centre, Kara) experience reduced April–October totals, while bimodal zones (Plateaux, Maritime) see weakened long rains (April–July) but enhanced short rains (September–October). At the same time, rainfall intensity has increased, with maximum 1‑day totals (RX1DAY) rising by about 20 mm nationally and over 25 mm in Savanes, alongside positive trends in other intensity indices (RX5DAY, R95p, R99p, SDII) that point to more severe events. Dryness has intensified through longer dry spells, with consecutive dry days increasing by around 17 days—especially in Maritime and Plateaux, where a drier November–March season dominates—and multi‑month drought severity (SPEI12) shifting from mildly wet conditions in 1961–1990 to significantly dry values in 2015–2024, following clear negative trends since the early 1950s. The length of the rainys season has also experienced remarkable variations.

ENSO modulates Togo’s temperatures through a negative correlation between SOI and mean temperature, yielding warmer (coler) anomalies during El Niño (La Niña) years, with the strongest effects in Savanes. El Niño boosts warm nights (higher TN90p) and suppresses cold nights (lower TN10p), while La Niña produces the reverse pattern. Annual rainfall totals correlate weakly and mostly non‑significantly with ENSO, but intensity indices (SDII, RX1DAY) show stronger responses: more intense events during La Niña north of 7ºN and larger 1‑day extremes during El Niño in Maritime. Gulf of Guinea SSTs exert a direct influence, with warmer SSTs raising temperatures and warm extremes while reducing cold extremes across Togo—especially in the south—enhancing rainfall and shortening dry spells there, but reducing rainfall and lengthening CDD in the north, thus highlighting contrasting meridional hydroclimatic responses. El Niño combined with warm Gulf SSTs generates the warmest and wettest conditions, whereas La Niña paired with cool SSTs yields the coldest and driest, producing national contrasts of about 0.8 ºC and 307 mm in annual rainfall between these extremes.

This analysis is supported by the CLIMSA, CREWS and UNCLIAFRO (PID2024-158042OB-I00)