PourDay reads the weather at your job site and tells you whether it's safe to pour concrete today — GO, CAUTION, or WARNING. Built on the ACI 305R evaporation formula, so when your slab cracks six months from now, it won't be because nobody checked.
You checked the weather. You made the call. The pour looked clean. Then six months later the slab maps and crazes — and now everyone's pointing at the foreman. Weather apps weren't built for concrete. PourDay was.
When the wind picks up and the slab's warm, you've got maybe two hours before it skins over. By the time you notice, it's too late to recover the finish.
Plastic shrinkage cracking happens in the first few hours after placement. You won't see it the day of. You'll see it on the callback. The fix? Don't let it happen.
Canceling at 5am means idle crews, short-load fees, and a project manager you don't want to call. Knowing two days out is the difference.
PourDay replaces gut calls with data-driven decisions in seconds.
Launch PourDay on your phone or any device. Input your location and get current weather conditions for your job site.
Using the evaporation rate calculation based on ACI 305R and live weather data — temperature, humidity, wind speed, and concrete temperature — PourDay computes your real-time evaporation rate.
Capture weather, evaporation rate, mix design, and supplier info automatically. Build a complete record your crew and project managers can rely on.
Schedule around or plan for high evaporation based on our 16-day forecast and hourly projections. Stay proactive, not reactive.
Every feature exists because a concrete contractor asked for it.
Real-time evaporation rate computed from current weather conditions, updated continuously throughout the day.
Plan pours up to 16 days out. See projected evaporation rates and status indicators for every day in the forecast window.
Log every pour with conditions, mix design, and outcome. Generate PDF reports for QA documentation and project records.
PourDay works for any job site in the US. Enter your zip code and get hyper-local conditions for your exact location.
No subscription, no paywall, no premium tier. PourDay is built for the concrete industry and free to use.
“Especially with the changes in cement in the last 2 years, if you are not tracking and scheduling around evaporation for slab pours you are putting yourself at risk.”
From ticket to finish, PourDay captures the data that protects your work and keeps your crew accountable.
Record mix details, concrete supplier, and ticket numbers for every load that hits your site.
Automatically capture weather, evaporation rate, and GO / CAUTION / WARNING status at the time of each pour.
When a crack shows up six months later, your pour log proves the conditions were right.
Export pour logs and mix records for project managers, inspectors, and engineers.
Four numbers decide it: air temperature, relative humidity, wind speed about 18 inches above the slab, and your concrete temperature. Run them through the ACI 305R evaporation formula and you get a number — anything over 0.15 lb/ft²/hr means you're flirting with plastic shrinkage cracking. PourDay does the math for you, live, using weather data for your exact job site, and gives you a GO, CAUTION, or WARNING. No nomograph, no spreadsheet.
Three situations to walk away from: (1) Air temp below 40°F and falling — hydration stops cold and the slab won't gain strength. (2) Air temp above 90°F with low humidity and wind — evaporation runs away and the surface skins over before you can finish. (3) Heavy rain in the forecast within the first 4–8 hours after placement — it'll wash out your finish and your air content. PourDay flags all three automatically.
Initial set is 4–8 hours. You hit roughly 65–75% of design strength at 7 days, and 100% at 28 days — that's the number on your cylinder breaks. But here's the catch: those numbers assume you didn't lose moisture during placement. If high evaporation cracks the surface in the first two hours, no amount of curing fixes it. That's the part most contractors learn the hard way.
Most premature cracking — the kind that shows up weeks or months later — traces back to one of three things that happened on pour day: too much evaporation pulling moisture from the surface (plastic shrinkage), too much heat accelerating the set, or restraint cracks from a slab that wasn't jointed properly. PourDay can't fix bad jointing. It can absolutely tell you when conditions will cook your slab.
There's no single number — it's the combination. 95°F with 60% humidity and no wind is fine. 85°F with 20% humidity and a 15 mph wind is dangerous. ACI 305R gives you the real answer with the evaporation rate calc, which is what PourDay runs for you in real time.
We pull from Open-Meteo, a professional-grade weather API used by meteorologists. 0–3 days out is dead reliable. 4–16 days is directional — good enough to schedule around, not good enough to bet a pour on without re-checking the morning of.
ACI 305R draws the line at 0.15 lb/ft²/hr. Above that, surface moisture leaves faster than bleed water can replace it, and you start losing the finish. That threshold matters even more now with Type 1L blended cement, which has less bleed water to begin with.
Yes. Every pour, every load, every mix design, every ticket — log it once and it's saved with the weather conditions and evaporation rate at that exact time. When something goes sideways six months later, the paper trail is right there.
Anywhere in the US. Drop in a job site zip code and you get hyper-local conditions for that spot. We built it in Kansas City but the math doesn't care where you're pouring.
Yes — fully free for contractors. No subscription, no paywall, no "premium" tier hiding the real features. Steller Concrete built it because we got tired of guessing, and figured the rest of the industry was tired of it too.
Real-time pour conditions. Mix and pour logging. Built by a concrete crew, for concrete crews. Always free.