Notes
How hot are summers in St. Johns County?
Summer is hot, humid, and built around afternoon thunderstorms from roughly June through September. The Atlantic is warm, school calendars and pool schedules matter, and people who only visit in March sometimes underestimate August. If air-conditioning, shade, and a realistic outdoor hour are not in your plan, this climate will feel like a different country.
Last reviewed September 21, 2026.
Northeast Florida is not South Florida, and it is not New England with palm trees. It is a humid subtropical coast. The Florida Climate Center publishes 1991–2020 normals for the St. Augustine station (COOP 087826). July’s average high is 91.0°F with a low of 73.8°F. August is 89.9°F / 74.2°F. June and September stay in the high 80s. Those are averages. Heat index on a still afternoon is the number your body will remember.
Rain is part of the heat. The same normals put annual precipitation at 50.64 inches, with June, August, and September as the wetter months (6.27, 7.18, and 7.18 inches). The local pattern is familiar by July: a bright morning, a building tower, a hard shower, a steaming evening. You plan outdoor work early. You treat the pool as infrastructure. You do not schedule a 2 p.m. walk in August the way you would in Maine.
Winter is the consolation prize and the reason snowbirds exist. January’s average high in those normals is 67.5°F, with a low of 47.8°F. That is sweater weather, not a freeze-your-pipes identity — though brief cold snaps happen, and people from Minnesota still buy a jacket they use ten days a year. March and April are the flattering months, which is why we keep saying you should also come in summer.
Humidity is the character, not a footnote. Inland streets without a breeze can feel heavier than the beach. Afternoon storms raise mosquitoes and drop the temperature a few degrees that feel like mercy. Air-conditioning is not a luxury; it is how houses function. Ask about the age of the system the way you would ask about a roof.
Lifestyle adapts. Youth sports shift toward evening lights. School years start in the heat. The ocean stays swimmable long after a Midwest lake would have given up. If you hate being outdoors when it is 90 and wet, you will live in a corridor from car to building to car and wonder why you moved. If you can make peace with early walks, water, and a real siesta energy, August becomes a season instead of a verdict.
Check the seven-day forecast on this site when you are planning a visit. Then believe August more than the week you lucked into. We did not grow up in this climate. We learned it. Ask if you want the unvarnished version for your month of arrival.