There is great variety in the Ecuadorian climate, which is largely determined by altitude and terrain. The mountain valleys have a year-round temperate climate and a humid subtropical climate exists in coastal areas and rainforest in lowlands. The country has two primary seasons that are differentiated by the distribution of rainfall: the rainy season and the summer or dry season. The four regions that form the country have very distinct climates. The coast has a tropical climate and a rainy season that extends from the end of December to May; the thermal regime is characterized by a 2°C to 3°C variation between the hottest and coldest months. The inter-Andean valleys have a temperate climate and rainy season from October to May and a dry season from June to September; average monthly temperatures are about 14.5° C in the rainy season and 15° C in the dry season. The Amazon Region in the eastern part of the country experiences rainfall throughout the year; the average temperature is around 21° C during most months of the year. The Island region comprising the Galapagos Islands has a climate similar to that of the Coastal Region. Average temperature is about 25°C to 26°C during the rainy season (December to May) and 21°C to 22°C during the dry season (June to November), mainly owing to the influence of the cold Humboldt current. The climate of the country is strongly marked by the influence of oceanographic factors, of atmospheric circulation and marine currents because they are in the Intertropical Convergence Zone (ITCZ).
Climate variability in Ecuador is closely related with the El Niño Southern Oscillation (ENSO) with increased rainfall and floods in the coast and Western Andes, and droughts in the Northern and Eastern areas. In the medium- to long-term, climate change trends in Ecuador are expected to result in major impacts for the country. These include the intensification of extreme climatic events (e.g. ENSO); sea level rise; increased retreat of glaciers; decrease in annual runoff and increased vulnerability of water resources; increased vulnerability to floods and prolonged droughts; increased transmission of dengue and other tropical diseases; the expansion of invasive species populations in the Galapagos and other sensitive ecosystems of continental Ecuador; and the extinction of certain species.
- Ecuador experiences year-round rainfall with the highest rainfall occurring May to July. Ecuador experienced increases in average as well as minimum and maximum temperatures between 1960 and 2010.
- Maximum temperatures have risen between 1°C per decade in the high mountains, and 0.6°C per decade in the sub-paramo regions.
- The number of warm nights have increased, while the number of cold nights have decreased.
- Ecuador has a high degree of variability in its precipitation trends and precipitation varies across regions.
- Increasing rainfall has occurred in the eastern areas over Ecuador’s Amazon rainforest, in the Sierra and along the northern coast, especially in the coastal areas of the provinces of El Oro, Guayas, Santa Elena and Manabí.
- Annual precipitation increased by 33% in the Coastal Region and by 8% in the Inter-Andean Region.
- Retreat of glaciers in the Andean region is significant is about 20 to 30% in the last 30 years.