There is no real summer and winter in Ecuador. Because Ecuador sits on the Equator, there is very little seasonal variation. The sun rises and sets every day at the same time, which means we have 12 hours of sunlight, every day, all year long.
Climate in Ecuador depends more on altitude and geography than seasons. In Ecuador, we enjoy a YEAR-ROUND riding season!
Climates range from equatorial rainforest in the Amazon to perpetual snow on the top of active volcanoes. There are dry, desert like areas where it rarely rains and there are warm, sunny beaches. In a single day's ride, you can experience all four seasons and a full continent's worth of climatic changes. In the highland towns, temperatures are generally 50-75 degrees fahrenheit during the day, while on the coast temperatures can vary from 70-90 degrees fahrenheit. The weather in the Amazon basin is constant: warm and humid. However all of these general rules are complicated by various microclimates found around the country.
The driest months in the Andes are May - December and the best weather on the coast is usually January- March.
It seems to be impossible to predict the weather in the highlands. We have yet to find a source for a decent forecaster. If you look at the forecast in the Andes, the forecast will just about ALWAYS say that it is going to rain. DO NOT LISTEN to the forecast! They are terribly incorrect. If there is even a slight chance of rain somewhere up in the clouds of the Andes, they will mark "rain" in the forecast.
Generally if it rains in Ecuador, it does not rain for long or all day. If you continue riding, you will pass through into a completely different climatic zone. Chances are that you will have great weather in Ecuador, especially if you ride into different geological areas and microclimates around the country.