St Johns Weather OverviewScoresFors & AgainstsWeatherPhotos Average Temperature Jan 81 °F27 °C Feb 81 °F27 °C Mar 81 °F27 °C Apr 81 °F27 °C May 82 °F28 °C Jun 84 °F29 °C Jul 86 °F30 °C Aug 86 °F30 °C Sep 86 °F30 °C Oct 86 °F30 °C Nov 84 °F29 °C Dec 82 °F28 °C Humidity Jan 63% Feb 63% Mar 62% Apr 63% May 66% Jun 68% Jul 65% Aug 68% Sep 66% Oct 65% Nov 66% Dec 65% Rain Jan 15mm Feb 15mm Mar 13mm Apr 13mm May 30mm Jun 88mm Jul 50mm Aug 63mm Sep 43mm Oct 42mm Nov 37mm Dec 37mm Clouds Jan 20% Feb 23% Mar 20% Apr 22% May 54% Jun 45% Jul 20% Aug 31% Sep 39% Oct 31% Nov 25% Dec 32% Sun Jan 8UVI Feb 10UVI Mar 11UVI Apr 11UVI May 9UVI Jun 10UVI Jul 11UVI Aug 10UVI Sep 10UVI Oct 9UVI Nov 8UVI Dec 7UVI