You can pour concrete between about 50°F and 90°F. ACI guidance treats roughly 50°F as the practical minimum air and mix temperature (55°F at placement for thin slabs under 12″) and about 95°F as the maximum when the concrete goes down. Outside that band it still pours — it just needs precautions.
Concrete is happiest poured between about 50 and 60°F. Push too far in either direction and curing goes wrong — cold stalls it, heat rushes it. Both are workable with the right precautions.
What's the coldest temperature to pour concrete?
Below about 40°F, cold slows curing to a crawl, and fresh concrete that freezes can be permanently ruined. Don't pour on frozen ground. Use warm mix water or an accelerator, protect the slab with insulating blankets, and keep it above freezing until it has gained enough strength. Expect every milestone to take longer — cars may need more than the usual 7 days.
How hot is too hot to pour concrete?
Above about 90°F, heat and wind pull moisture out fast, causing flash setting and surface cracking. Pour in the early morning or evening, dampen the subgrade and forms first, have enough hands to place and finish quickly, and start wet-curing immediately. A retarder can buy working time.
The takeaway
Aim for mild conditions when you can schedule it. When you can't, the rule is simple: in the cold, keep it warm and wet long enough; in the heat, slow the moisture loss and finish fast. Either way, plan your volume ahead with the slab calculator so the pour goes smoothly.
Common questions
What temperature is too cold to pour concrete?
Below about 40°F curing slows badly, and freezing can ruin fresh concrete. Pour above freezing and protect the slab, or wait.
Can you pour concrete in hot weather?
Yes, with care — pour early or late, keep everything damp, finish quickly, and cure immediately to prevent cracking.
What is the best temperature to pour concrete?
Roughly 50 to 60°F, with moderate humidity and low wind.