How cold is too cold to pour concrete?
Short answer: when the air is at or headed below 40°F, you're in cold-weather concreting territory, and fresh concrete must not freeze for its first 48 hours. Pouring at 45°F is fine only if the next two nights stay well clear of freezing.
The 40°F line (ACI 306)
“the conditions of cold weather concreting exist when the air temperature has fallen to, or is expected to fall below, 40°F (4°C) during the protection period”— NIH technical bulletin quoting ACI 306R-16Note the word expected: it's not just the temperature when the truck arrives, it's the forecast for the days after. Bagged DIY mixes say the same thing in plainer words:
“Air, mix and substrate temperatures should be between 40°F (4°C) and 90°F (32°C) with no rain in the forecast within 24 hours”— Sakrete High Strength Concrete Mix data sheetThe first 48 hours: don't let it freeze
“concrete should be protected from freezing until it attains a minimum compressive strength of 500 psi … about two days (48 hours) after placement”— NIH technical bulletin “Protect concrete from freezing during the first 48 hours.”— QUIKRETE 5000 data sheetFairsky's concrete verdict checks the lowest temperature in the 48 hours after you finish: any hour at or below 32°F is a NO; lows between 32°F and 40°F make it borderline and call for insulating blankets or heat.
Curing compound has its own limit
“Curing compounds should not be applied if rain or temperatures below 50 degrees F (10 degrees C) are expected within 24 hours”— QUIKRETE 5000 data sheetToo hot is a problem too
Hot weather (ACI 305) is defined by what it does rather than a single number: conditions that “impair the quality of freshly mixed or hardened concrete by accelerating the rate of moisture loss and rate of cement hydration.”— STRUCTURE magazine Wind and low humidity add to it: “Plastic shrinkage cracking becomes a strong possibility when the rate of evaporation exceeds 0.2 lb/ft2/hr (1.0 kg/m2/hr)”— Euclid Chemical Fairsky flags pours above 85°F as borderline and says no above 90°F (Sakrete's limit).
Fairsky's concrete rule in one list
- 4 daylight hours to place and finish.
- 40°F or warmer while pouring (32–39°F borderline); 85°F or cooler (86–90°F borderline).
- Rain chance 20% or less while pouring, and 24 rain-free hours after.
- Above 32°F for the next 48 hours (32–40°F: plan blankets).
- Wind 20 mph or less (a Fairsky default).
How many cold-weather months your city gets
From NOAA's 1991–2020 normals, the number of months whose average low is 40°F or colder. Averages hide cold snaps and warm spells, so each city page also has a live verdict.
7 months with normal lows of 40°F or colder
Denver, CO · Grand Rapids, MI · Colorado Springs, CO · Springfield, MA · Madison, WI · Spokane, WA
6 months with normal lows of 40°F or colder
Detroit, MI · Minneapolis, MN · Providence, RI · Milwaukee, WI · Buffalo, NY · Hartford, CT · Rochester, NY · Worcester, MA · Albany, NY · New Haven, CT · Boise, ID · Akron, OH · Ogden, UT · Syracuse, NY · Provo, UT · Toledo, OH · Scranton, PA
5 months with normal lows of 40°F or colder
Chicago, IL · Boston, MA · Seattle, WA · St. Louis, MO · Pittsburgh, PA · Cincinnati, OH · Kansas City, MO · Columbus, OH · Indianapolis, IN · Cleveland, OH · Nashville, TN · Oklahoma City, OK · Louisville, KY · Richmond, VA · Salt Lake City, UT · Omaha, NE · Bridgeport, CT · Albuquerque, NM · Knoxville, TN · Allentown, PA · Dayton, OH · Greensboro, NC · Des Moines, IA · Wichita, KS · Durham, NC · Harrisburg, PA · Chattanooga, TN · Lancaster, PA
4 months with normal lows of 40°F or colder
New York, NY · Washington, DC · Philadelphia, PA · Baltimore, MD · Charlotte, NC · Virginia Beach, VA · Tulsa, OK · Winston-Salem, NC
3 months with normal lows of 40°F or colder
Atlanta, GA · Portland, OR · Raleigh, NC · Memphis, TN · Birmingham, AL · Greenville, SC · El Paso, TX · Columbia, SC · Little Rock, AR
2 months with normal lows of 40°F or colder
Dallas, TX · Las Vegas, NV · Stockton, CA · Jackson, MS · Modesto, CA
1 month with normal lows of 40°F or colder
Fresno, CA · Bakersfield, CA · Augusta, GA
No months with normal lows of 40°F or colder
Los Angeles, CA · Houston, TX · Miami, FL · Phoenix, AZ · Riverside, CA · San Francisco, CA · Tampa, FL · San Diego, CA · Orlando, FL · San Antonio, TX · Austin, TX · Sacramento, CA · San Jose, CA · Jacksonville, FL · Tucson, AZ · Baton Rouge, LA · McAllen, TX · Oxnard, CA · Sarasota, FL · Charleston, SC · Cape Coral, FL · Lakeland, FL · Daytona Beach, FL · Melbourne, FL
Sources
- NIH technical bulletin: cold weather concreting (quoting ACI 306R-16)
- QUIKRETE 5000 data sheet
- Sakrete High Strength Concrete Mix data sheet
- STRUCTURE magazine: cold and hot weather concrete
- Euclid Chemical: preventing rapid evaporation
Quotes were checked on the linked pages in October 2026. Thresholds marked as Fairsky defaults are our own conservative choices, not citations. Product labels differ; your label wins.
Questions
What temperature is too cold to pour concrete?
By ACI 306R-16 (as quoted in an NIH technical bulletin), cold-weather concreting conditions exist when the air temperature has fallen to, or is expected to fall below, 40°F during the protection period. Bagged mixes like Sakrete call for air, mix and substrate between 40°F and 90°F.
How long does new concrete need to be protected from freezing?
The NIH bulletin says concrete should be protected from freezing until it reaches 500 psi, about two days (48 hours) after placement. QUIKRETE's data sheet also says to protect it from freezing during the first 48 hours.
Can it rain on fresh concrete?
Sakrete's data sheet says no rain in the forecast within 24 hours of placing. Fairsky's concrete rule wants 24 rain-free hours after the pour.
Fairsky is not a substitute for official warnings. For warnings, go to weather.gov.
Live forecasts: National Weather Service / NOAA (public domain), fetched by your browser. Climate averages: NOAA NCEI U.S. Climate Normals, 1991–2020 (public domain). Project thresholds: product data sheets, ACI and university extension guidance, linked on each page; your product’s label wins.