Ilocos Norte has Type 1 climate which is characterized by two pronounced seasons, wet and dry.
Based from 31 years (1976-2006) of rainfall data, the annual rainfall in Batac, Ilocos Norte is 2001.3 mm. About 80% of this occur from June to September. Rainfall is principally brought about by the Southwest Monsoon. Tropical cyclones and thunderstorms also contribute to the rainfall received in the province.
Annual evaporation is 1780.0 mm. Highest evaporation generally occur during the month of April with about 6.3 mm/day. Highest solar radiation, maximum air temperature and lowest relative humidity are observed during the particular period.
Superimposing evaporation data to that of the rainfall data, it can be observed that about 13% of the rainfall occurring is considered as surplus rainfall.
On the average, daily solar radiation is 18.6MJ/m2/day. Solar radiation are low during the cold months of the year. Values of relative humidity are high and minimum air temperature are low during these periods.
The annual mean daily temperature is 27°C. The coolest month of the year is January (18.5°C) while April, the hottest (33.9 °C).