Summary.1In connexion with an investigation of the reproduction of organisms in a climate which varies little during the year, meteorological observations were made from September 1933 to August 1934 at Hog Harbour, Espiritu Santo, New Hebrides (15o15′ S. latitude). Special attention was paid to the measurement of the climate in which the animals actually live, namely in the rain‐forest.2In general, the climate at Hog Harbour is hot and wet from June to October, and slightly hotter and considerably wetter from November till May. There is no dry season, the least wet month having, on the average, about twice as much rain as the wettest month in England. The year under investigation conformed to the average except that April and May were less wet than usual.3The mean temperature only varied by 2o‐l C. (3o‐8 F.) between the hottest and coldest months. In England during the same period the seasonal change was about eight times as great.4The distribution of rainfall is exceptionally unseasonal for a tropical region, since the wettest month receives on the average only 2–5 times as much rain as the least wet. An analysis of meteorological data from the whole of the tropics shows that such a low figure as this is very rare.5The cooling power of the atmosphere, as measured by the kata‐thermo‐meter, was greater in July and August than in the other months, but the difference was small.6There is no obvious seasonal distribution of daily hours of sunshine, but there appears to be much less ultra‐violet light in certain months (e.g. June) than in others.7The saturation deficiency of the atmosphere was almost uniform throughout the year, except that it was higher during April and May. The amount of evaporation varied considerably from month to month, without disclosing any distinct seasonal tendency.8Barometric pressure varied only very slightly during the year, but its variations were very regular and indeed constitute the most regular seasonal change observable