There's a special chemical mixed into the tank that keeps the stuff calm. Above this temperature it stops doing its job, and the chemical inside can start reacting on its own.
2h 42m 22s
At the rate it's heating up, the tank would hit 104°F around Sat, May 23, 10:00 PM PT.
How this countdown is calculated
Temperatures we've heard so far:
Fri 8:00 AM — Fri morning — first reading77°F
Sat 8:00 AM — Sat morning — gauge re-read90°F
That's 0.54°F/hr over 24hOfficials now say ~1°F/hr
Best guess for right now101.3°F
If you hear a new number on the news, change it here:
This is a guess, not a live thermometer. We only have two confirmed readings (above) and a rate firefighters mentioned out loud. The math draws a straight line from the latest reading using that rate. If the rate speeds up — which can happen as it gets hotter — these countdowns get shorter. Reaching one of these temperatures doesn't automatically mean an explosion; it means things are getting worse.
Watch live
Autoplays muted — tap the unmute icon for audio. BREAKING LIVE: Toxic Chemical Leak From 34,000-Gallon Tank (N18G).
Verbatim posts from OCFA (Orange County Fire Authority), the incident-command agency. Polled every 60 seconds.
Map — am I in the zone?
Red box = official evacuation zone (Trask Ave → Ball Rd, Valley View St → Dale St). Red dot = the tank. Green dots = shelters. Paste an address below to see exactly where it falls.
Cross-checked against the OC Sheriff Resources page (county-run shelters) plus individual city emergency alerts (city-run sites). For live capacity, call OC public info 714-628-7085.
Other reported options: Planet Fitness OC locations are letting evacuees use showers, Wi-Fi, and outlets free of charge; several Anaheim hotels are offering discounted emergency rates.
What we know so far — the basics
What's in the tankA chemical used to make plastic (called MMA)
How much34,000 gallons — enough to fill a swimming pool
Second tank nearby15,000 gallons — crews working to neutralize it so it can't be triggered
How hot it isAbout 90°F, getting hotter by 1°F every hour
Cities affected: Garden Grove, Stanton, Cypress, Anaheim (W), Buena Park, Westminster.
Analysis
🟡 ANALYSIS, NOT OFFICIAL. Everything below is independent reasoning from public reporting, transcribed OCFA briefings, and chemistry references. OCFA has not endorsed any probabilities. If officials say something different, trust officials.
What firefighters can actually try
Water spray cooling (current passive baseline).Unmanned hoses + sprinkler. Temp still rising at 1°F/hr — losing the race outright, but it's slowing the cure rate, which is part of the plan now.
Controlled cure — let it finish polymerizing slowly.What Covey publicly named as the "third option": keep cooling to slow the cure, hope the void space above the liquid absorbs pressure faster than it builds. If it works, you end up with a tank full of solid acrylic instead of a fireball.
Going downrange to neutralize the second tank.Crews already doing this since Friday night with manufacturer chemists. Goal: remove the 15k tank's explosive potential so the worst case stays bounded.
Diking, damming, and diversion.Staged for the failure scenario. Covey: divert spilled MMA to a downgrade holding area to keep it out of storm drains, the river, and the ocean.
Drill a fresh port (hot-tapping).Textbook fix for stuck valves on reactive monomers — not publicly mentioned in any OCFA briefing. The flammable vapor around the tank makes a spark catastrophic, but specialty contractors do this for a living.
Liquid nitrogen or refrigeration coil.Brute-force temperature drop. Heavy equipment, slow to mobilize, not in evidence.
Foam blanket over the area.Doesn't fix the chemistry but if it does blow, foam reduces the fireball size and slows the vapor cloud.
Diking and damming staged for this scenario. Down from earlier estimates because Covey's evening update signaled they're now trying to prevent any failure, not just steer toward a spill.
Controlled cure or new intervention works~30%
Up from earlier. Covey said tonight they brought in state-level experts to develop "completely outside the box" options and will "chase down those concepts" tomorrow. Plus the explicit controlled-cure path.
Uncontrolled slow leak~15%
Valve or seam gives up on its own. Bad — toxic vapor cloud — but containable with the foam and diking they're staging.
Cooling holds, they ride it out~3–5%
Down from earlier. Covey effectively ruled this out — cooling alone isn't winning. Some marginal probability remains for the trend to flatten without active intervention.
BLEVE (explosion)~7–10%
Down slightly. More time, resources, expertise applied; 15k tank work continues; no new temp spike reported. Still real but trending in the right direction.
Prediction history (2 earlier estimates)
Earlier snapshots, newest first. Kept for context — only the current estimate above is the one I'd stand behind right now.
After learning about the 15k second tankMay 23, 5:15 PM PT
Transcribed Covey's morning briefing revealed a second 15,000-gal tank near the failing one, plus that manufacturer chemists were already on-site. Added the explicit "controlled cure" outcome.
Controlled spill~50%
Controlled cure — slow polymerization without rupture~20%
Uncontrolled slow leak~15%
Cooling holds, they ride it out~5–8%
BLEVE (explosion)~8–12%
Initial estimateMay 23, 3:30 PM PT
First analysis after the Saturday morning OCFA briefing confirmed the temperature was rising (90°F, +1°F/hr) and the manufacturer chemists weren't yet publicly visible.
Is the heating rate linear or accelerating? Chain reactions like this tend to speed up once they start — the rate doubles, then doubles again. If a new reading shows the temperature jumping faster than 1°F/hr, the explosion odds climb fast.
Specifically: if tonight's update reports a temp above ~100°F (instead of the projected ~97°F), the rate is accelerating. If the next OCFA update skips the number entirely, that's a signal worth noting — silence on the number usually means it's worse than they want to say publicly.
Is the response itself the right one?
Critique of an active emergency response is fraught. OCFA has data we don't — internal pressure readings, structural scans, manufacturer guidance, tank-supplier specs. The points below are about what's visible from public communications (including transcribed briefings), not verified failures of their plan.
What they're getting right
Big evacuation perimeter, fast.40k+ people moved out within hours. Textbook BLEVE response — no civilians in the worst-case zone.
Honest public framing.Covey publicly walked back his own optimism: "Yesterday afternoon I did report… we thought we were reducing it… Unfortunately I had to say thought." Updating your own bad news live takes guts.
Clean chain of command.Chief Covey as incident commander, Dr. Regina Chinsio-Kwong as OC Health Officer, Cal OES backstop, Governor declaration. No turf war.
Manufacturer's chemist team on-site.Per Covey: "chemists from the emergency response team from the manufacturer" have been working with OCFA since Friday night. Right expertise, right place.
Went offensive when defense stopped working.Friday night they put crews downrange — with manufacturer chemists — to read the internal gauge directly and start neutralizing the 15k tank. Covey: "We did put them back in harm's way last night." Active intervention, not stall.
Spill-containment infrastructure being staged.Covey detailed prepping diking, damming, and diverting the liquid to a downgrade holding area if the tank fails — explicitly to keep MMA out of storm drains and the ocean. Environmental contingency, not just life-safety.
Naming the "third option" publicly.Covey explicitly broke out of the binary "spill OR explode" framing with a controlled-cure option: let the MMA polymerize slowly into solid plastic, with the void space above absorbing pressure. Whether it works is uncertain — but admitting Option 3 exists is correct.
Bringing in state-level experts to develop new options.Per Covey's 5:58 PM update: "we brought in subject matter experts from all across the state to think completely outside the box and we had some really good productive conversations today." Escalating beyond local capacity — the right move when the standard playbook is losing.
Drone polling every 10 minutes.Per the evening update: "We got the drones on them every 10 minutes watching for any temperature changes or spikes." Not as good as internal telemetry, but near-continuous external monitoring is materially better than I'd assumed earlier.
Open questions about the approach
Is the controlled cure actually working?
Covey described the cure-slowly-and-bleed-pressure strategy hopefully but admitted they're still trying to "validate" it. With temp still rising at 1°F/hr, the cure is happening but the void space may not be absorbing pressure fast enough. No public measurement of internal pressure has been released — that's the metric that would tell us if this strategy is winning.
Internal telemetry still missing
Covey's evening update says drones poll the tank exterior every 10 minutes — that's better than I credited earlier. But the gauge they had to physically enter the site to read on Saturday morning is still the only internal data point. A 34k-gallon reactive-monomer tank near a residential area should have continuous internal pressure + temp telemetry. It doesn't. Regulatory gap worth flagging after the incident.
Hot-tap option not mentioned in any briefing
Drilling a fresh port into the tank is the textbook fix for a stuck valve on reactive monomers. Covey did say they're "bringing people in from all over the country" for ideas, so it may be on the table internally. But it hasn't been named publicly. Worth a sentence either way.
What's the actual status of neutralizing the 15k tank?
Covey said Friday night they went offensive to neutralize the 15,000-gal second tank — material because if the failing 7k tank blows, it could trigger the bigger one. But no public statement on progress: not emptied, half-done, almost done? Silence is a signal. If this tank were neutralized, OCFA would announce it.
Time is asymmetric
Controlled cure works if the rate stays linear. Exothermic polymerizations have a habit of going non-linear once they accelerate. Every hour of cure-and-wait trims the window for switching to a different intervention. There's been no public mention of a "if temp hits X, we switch to Plan Y" trigger.
Blast map is published but not parameterized
OCFA's Saturday briefing showed a six-zone map (3 blast damage circles + 3 toxic-impact zones — red/orange/yellow). Useful — but no actual radii in feet or miles have been published, so a resident can't tell which damage circle their house sits in. A picture isn't a substitute for distance numbers.
The single question worth answering publicly
"What's the current internal pressure inside the failing tank, and how much margin do we have before the void space is overwhelmed?"
The controlled-cure strategy lives or dies on the void-space-vs-pressure equation. Temperature is only a proxy. Pressure is the metric that tells us whether Covey's "third option" is winning or losing — and it hasn't been shared publicly.
Why — what's happening, in plain words
The tank holds a liquid that really wants to turn into plastic. To stop that from happening, the company mixes in a tiny amount of a "safety chemical" that keeps it calm. That safety chemical only works when the liquid stays cool and has air mixed in.
The tank is heating up. As it heats, the air gets pushed out and the safety chemical stops working. Once that happens, the liquid starts turning into plastic — and that process gives off heat. More heat means it turns into plastic faster. Faster means even more heat. That's the loop firefighters are trying to break.
Wait, there are two tanks?
Yes. Per OCFA Incident Commander Craig Covey's Saturday-morning briefing (we transcribed it from his X video update — it's not in most press coverage):
Tank #1 (the failing one): ~7,000 gallons of MMA still in the original 34,000-gal storage tank. Heating up, can't be accessed normally because of the broken valve. This is the one the countdown is about.
Tank #2 (nearby): ~15,000 gallons. Friday night, crews went "offensive" with the chemical manufacturer's emergency response team to start neutralizing this second tank — meaning making it inert so it can't be triggered if Tank #1 explodes. This is good and important work, because the worst-case scenario (Tank #1 BLEVE setting off Tank #2) would be much bigger.
What does the chemical smell like? How would I know if it reached me?
MMA has a strong, sweet, fruity smell — OCFA's own description. If you're outside the evacuation zone but suddenly notice a sweet/fruity odor in the air, that may be vapor drifting from the tank. Don't stand around to investigate: move indoors, close windows, turn off any AC that pulls in outside air, and call the OC public info line (714-628-7085).
The fruity smell is detectable at very low concentrations — you'll smell it well before it reaches a level that's actually dangerous to breathe. So smelling it isn't the same as being in immediate harm — but it is a signal to take precautions.
What do the colors on OCFA's map mean?
OCFA's briefing map has six zones — three circles for "if it explodes" and three outer zones for "if the gas leaks":
Blast damage circles (closest to the tank): • Innermost — severe structural damage • Middle — moderate damage • Outer — light damage still possible
Gas/vapor zones (broader area): • Red — flammable; could catch fire or flash if vapor reaches this area • Orange — immediate health danger; breathing this would cause injury • Yellow — odor threshold; you'd smell it but it's not harmful at this level
OCFA hasn't published the actual distances yet — there's no way to tell from outside which circle your address falls in.
Where is the broken valve? Can't they just fix it?
Officials haven't shown a picture or said exactly which valve. All we know from press conferences is that OCFA Chief Craig Covey described it as "broken and gummed up," and that the damage stops crews from safely getting to the chemical inside.
Big chemical tanks like this one have several valves — usually on top (for adding chemicals or venting pressure), on the side (sampling ports), and on the bottom (draining). For this kind of tank in an aerospace plant, the broken valve is most likely the one they would normally use to drain the tank or add a stabilizer. Without it working, they can't offload the liquid, can't pump in fresh "safety chemical," and can't relieve the pressure that's building up inside.
Why not just send someone in to swap the valve? Three reasons: (1) the area right next to the tank has poisonous fumes leaking out, so anyone close enough to touch the valve is in serious danger; (2) the gas around the tank is flammable, so a single spark from a wrench could start a fire or set off the explosion everyone is trying to prevent; (3) the heat may have warped the tank itself, which can seize the valves into the metal so they can't be removed even with the right tools.
Why is it heating up in the first place?
A valve on the tank broke. That let a tiny bit of warming start — maybe from sun on the tank, maybe from a small reaction inside. Once the liquid got a little warmer, the air mixed into it started bubbling out. The "safety chemical" only works when there's air mixed in, so it stopped doing its job.
Now the liquid is slowly turning into plastic, which gives off heat. That heat pushes more air out, which makes more plastic, which makes more heat. It's a feedback loop — the warmer it gets, the faster it gets warmer. Firefighters can't open the tank to pour in fresh safety chemical because the broken valve is in the way and the gas inside could catch fire.
Why are they spraying water on it?
To pull heat out faster than the chemical is making it. If gas starts leaking, the water also catches the gas in the air so it doesn't drift over neighborhoods.
What could actually go wrong?
The tank leaks: a seam pops and 6,000–7,000 gallons spill into the parking lot. The fumes are poisonous and can catch fire, but it's a smaller problem.
The tank explodes: if the heat loop wins, pressure builds up inside until the tank bursts. That's a much bigger blast, with a much bigger poison cloud.