The 31st parallel south is a circle of latitude that is 31 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, Africa, the Indian Ocean, Australasia, the Pacific Ocean and South America. At this latitude the sun is visible for 14 hours, 13 minutes during the December solstice and 10 hours, 4 minutes during the June solstice.

Around the world

Starting at the Prime Meridian and heading eastwards, the parallel 31° south passes through: ! scope="col" width="125" | Coordinates ! scope="col" | Country, territory or ocean ! scope="col" | Notes ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean ! scope="row" | 🇿🇦 ! scope="row" style="background:#b0e0e6;" | Indian Ocean ! scope="row" | 🇦🇺 ! scope="row" style="background:#b0e0e6;" | Pacific Ocean ! scope="row" | 🇨🇱 ! scope="row" | 🇦🇷 Passing near the cities of Paraná (31°44′S 60°32′W) and Santa Fe (31°38′S 60°42′W). ! scope="row" | 🇺🇾 ! scope="row" | 🇧🇷 ! scope="row" | 🇺🇾 ! scope="row" | 🇧🇷 ! scope="row" style="background:#b0e0e6;" | Atlantic Ocean