Phillipsburg's climate is either a humid subtropical climate (Köppen "Cwa") or a humid continental climate (Köppen "Dwa"). Phillipsburg meets the criteria for a true winter dry season under the Köppen climate classification, which is a rare for its region and for the United States outside of South Florida. The average temperature for the year in Phillipsburg is 51 °F (11 °C), and the average yearly precipitation is 23.3 inches (594 mm). On average, January is the coldest month, July is the hottest month. May is the wettest month. The hottest temperature ever in Phillipsburg was 120 °F (49 °C) in 1936; the coldest temperature ever was -28 °F (-33 °C) in 1989.