Guinobatan falls under the Type II of the Modified Coronas Classification system of climate. This type of climate has no significant dry season and with a very pronounced rainfall under the influence of the northeast monsoon, prevailing from November to January. Pronounced rainfall under the influence of the Southwest monsoon prevails from June to October. The wettest month is September with an average precipitation of 292.5 mm (Table l). The driest month is February with 55.0 mm average rainfall (about 155.5 mm maximum and 14.7 mm minimum rainfall). The hottest month of the year is June while the coldest months are December to February with, April and may have the longest sunshine hours and the shortest in September with 14,2 hours/day. Monthly relative humidity ranges from 82% in March through May and 86% in December.
Typhoon usually affects the Region within the months of July to December with the highest frequency of occurrence from August to October. For Southern Luzon section including the municipality, the prevailing wind direction is northeast from January to May, and the southwest winds in June to December. The average prevailing wind speed is 1.20 meters per second, the highest at 1.90 meters per second in February and the lowest at 0.60 meters per second in July to August. The other4 climatic threat to the municipality is the inter-tropical convergence zone (ITCZ) that affects the Bicol Region from May to later part of October. The ITCZ is considered as a distributed weather condition consisting of widespread cloudiness, precipitation and moderate to strong winds. At times, it causes rainfall that lasts for eight (8) days or more.