Solomon Islands Climate
The Solomon Islands, lying within 12 degrees latitude of the equator and more than 1500km from the nearest continent, has a climate typical of many tropical areas, being characterised by high and rather uniform temperature and humidity and, in most areas, abundant rainfall in all months. Rainfall is the least uniform of these climatic elements, as topographical effects cause significant variations between locations. The Islands, because of their low latitude, are less subject to the damaging effects of tropical cyclones than elsewhere in the Southwest Pacific, though cyclones still pose a serious threat each year.
The weather and climate of the region can be explained largely by the seasonal movement and development of the equatorial trough; a belt of low pressure that migrates between hemispheres following the apparent movement of the sun, and the subtropical ridge of the southern hemisphere (a belt of high pressure typically located at about latitude 30 to 35 degrees south).
From about January to March the equatorial trough is usually found close to, or south of the Solomons, and this is a period of West to North-westerly monsoonal winds. The heaviest rainfall at most places also occurs at this time. The equatorial trough is in the Northern hemisphere from May to October and the Islands then lie within the region of the Southeast trade winds; the trades being the stronger and more persistent winds blowing out from the subtropical ridge towards the equatorial trough. These winds are moisture bearing, having had a long path over the ocean and heavy rainfall can also occur during the South-easterly season, especially on the windward side of the Islands. The transition months between the two seasons are marked by a greater frequency of calm winds.