The Independent State of Samoa lies just east of the International Date Line and South of the Equator Latitude -13 deg S, Longtitude -171 deg W. Due to its geographical location, our climate is characterized by uniform temperature, pressure, abundant rainfall and high humidity.
Samoa has two distinct seasons, the "Hot and Wet" season, is from November to April. The "Cool and Dry" season is from May to October.
Samoa's annual mean rainfall ranges from 3000 to 6000 millimeters. About 70% of the annual mean rainfall is observed during the Hot and Wet season.
Topography plays a vital role in the rainfall distribution, the windward side (south to southeast) of the main islands receive more rainfall than the rain-shadowed side mainly in the north to northwest regions.
El Nino Southern Oscillation (ENSO) is the main driver of Samoa's rainfall. El Nino tends to bring about lower than normal rainfall for Samoa, associated with droughts and forest fires. La Nina on the other hand are generally associated with above normal rainfall, associated with flooding of low-lying areas (in and around Apia).
There is relatively small seasonal variation in temperature in Samoa. The mean annual temperature range from 26 to 31 degrees Celcius. Night temperatures are pleasantly cooler in the Dry Season, when southeast tradewinds dominate. Apia Mean minimum temperatures drop to 22 degree Celcius around July or August.The trade winds are traditionally recognized as "Tuaoloa" or "The Season of Plenty has passed" and believed to cause sickness in the local population.
Southeast trade winds dominate right throughout the island all year round. Warm westerly winds are consider to be associated bad weather conditions.
Samoans are well known navigators and have a traditional names for winds and direction
Winds from the North are called Toelau
Winds from the South are called Toga
Winds from the West are called La'i
Winds from the East are called Mataupolu
Winds from the North-West called La'i Toelau
Winds from the North-East called Vaitoelau
Winds from the South-West called La'i Toga
Winds from the South-East called Tuaoloa
Relative humidity is usually high in Samoa, around 80% or above.