Concrete can be poured in Orlando any month of the year. It cannot be poured equally well in every month, and the difference shows up as cracks a year later.
Here is the window we plan our driveway and patio work around, and why.
Why November through March
Concrete cures by a chemical reaction with water, and it needs that water to stay in the mix long enough to do its work. In the cooler, drier months the slab holds its moisture, the reaction runs evenly from top to bottom, and the concrete reaches its strength the way the mix was designed to.[1]
The ground helps too. Soil moisture is lower and more stable in winter, which means a compacted base stays compacted between the day we build it and the day we pour on it. That is why the local trade treats November through March as the ideal window.[1]
What summer does to a pour
Two things, and both are about water.
Heat. On a ninety-degree afternoon with sun on the slab, the surface of fresh concrete dries out before the concrete underneath has set. The top shrinks while the bottom has not, and the surface cracks in narrow random lines across the panel.[2] It also makes the concrete set faster, which shortens the time the crew has to finish it properly.
Storms. From June through September a storm rolls through most afternoons, and Orlando's can drop several inches in an hour. Rain on concrete that has not set washes the surface, weakens the top layer and ruins the finish. A pour that is not done and covered before the storm is a pour that gets redone.[2]
How we pour in summer anyway
People need driveways in July too, and a good crew handles it. We pour early, so the finish is done before the heat of the day. We watch the radar and do not start a pour the forecast says we cannot finish. We cure the slab properly rather than leaving it to dry, which on a hot day means keeping the surface damp or applying a curing compound so the water stays in the mix.[3] And we cut the control joints on time, so the shrinkage that does happen goes where we planned it.
Done that way, a summer pour is a good driveway. Done the other way, which is a crew finishing fast ahead of a storm and leaving, it is a driveway with surface cracks by Thanksgiving.
Planning around the season
The practical advice: if you can choose, choose the cooler months, and book early because the winter schedule fills with everyone who had the same idea. If you cannot wait, ask the contractor how they handle heat and rain. The answers you want to hear are early pours, radar, proper curing and joints on time.
Either way, the dates after the pour matter. Walk on it after a day or two, park on it after about a week, keep heavy trucks off it for a month while it reaches full strength.[3] That schedule is the same in January and July.
