There are several factors to consider before you can lay concrete in the rain. The first is the weather forecast. It is important to know the expected rainfall so you can adjust your schedule accordingly. Although the weather forecast is never 100% accurate, the heavy rains can damage the concrete. You can also prepare your site by locating downspouts in the area where you plan to lay the concrete. Make sure to remove any debris from cavities and cover the area with plastic to prevent water from collecting there.
Another factor is the type of rain. A heavier rain can cause more damage to the concrete. This is because it was not covered prior to the rain. In addition to causing surface damage, rain can wash out cement particles and weaken the concrete. Depending on the location of the pour, the water can also cause the concrete to crack, soften, and become unsealed. This can also result in weaker concrete, which can be difficult to finish.
In the event of rain, you may have to cover the concrete slab with tarps or plastic sheets. A contractor should also keep tie-downs nearby and put up canopy tents. If the rain is sudden, he or she should wait until the weather clears up. Smartphones are now an indispensable tool in monitoring the weather. If there is a slight chance of precipitation, you should put up plastic sheets and tie-downs.