San Guillermo, in Cagayan Valley, Philippines, is home to roughly 3,900 people in the Asia/Manila time zone at 16.7°N latitude.
In 2025, San Guillermo recorded an average annual temperature of 78°F. The hottest temperatures reached 97°F in June; the coolest were 65°F in February. Total precipitation for the year was 135 inches, with the wettest month being November.
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