WattMarkets

Day-ahead vs. real-time

Every afternoon the day-ahead market prices tomorrow, hour by hour. This page grades that bet against what the grid actually paid.

Two prices for every hour

Aug 18 · CT · 8-zone average- - day-ahead — real-time
$0$25$50$75$100
Spread by hour (RT − DA)

Where the misses landed

by zone and hour · click a zone to re-scope the chart above
settled under day-aheadsettled overnot yet gradeddeeper = bigger miss · exact numbers on hover

Zone rows rank by today's average miss. zone mean of the load-zone settlement point prices.

Today so far
—
real-time average vs — day-ahead
Settled under day-ahead
62%
of 534 hours since 2026-07-19
Biggest miss of the window
−$100.41
Jul 21 9:00 PM CT: priced $173.31, settled $72.90
Tomorrow's prices
~12:30 CT
tomorrow's prices publish about then

The premium by hour

average spread by hour
+$15−$1512AM: −$1.36 over 23 hours1AM: −$0.84 over 23 hours2AM: −$0.34 over 22 hours3AM: −$0.53 over 22 hours4AM: +$0.35 over 22 hours5AM: +$1.41 over 22 hours6AM: +$0.95 over 22 hours7AM: +$1.07 over 22 hours8AM: +$0.45 over 22 hours9AM: +$0.67 over 22 hours10AM: −$0.57 over 22 hours11AM: −$2.49 over 22 hours12PM: −$2.03 over 22 hours1PM: −$2.24 over 22 hours2PM: +$0.58 over 22 hours3PM: +$0.69 over 22 hours4PM: −$0.04 over 22 hours5PM: +$1.19 over 22 hours6PM: +$0.12 over 22 hours7PM: −$15.11 over 22 hours8PM: −$12.34 over 23 hours9PM: −$9.81 over 23 hours10PM: −$2.07 over 23 hours11PM: −$2.77 over 23 hours12AM6AM12PM6PM

Average of 534 paired hours since 2026-07-19. Fills in as the record grows.

The afternoon hours that decide 4CP are the hours day-ahead prices hardest. When this chart bulges violet after 2 PM, that is why.

Tomorrow is already priced

the day-ahead bet

Tomorrow's prices publish around 12:30 CT. Until then, today is still being graded above.

What is the day-ahead market?

ERCOT runs a voluntary day-ahead market that clears each afternoon. Buyers and generators lock in a price for every hour of tomorrow, published around 12:30 CT. The real-time market then settles what each hour actually cost, in 15-minute intervals.

What is DART?

Trader shorthand for the day-ahead to real-time spread. On this page the spread is real time minus day-ahead, so a positive number means the hour settled above its day-ahead price and a negative number means day-ahead paid a premium.

Why do the two prices differ?

The day-ahead price embeds a forecast of weather, demand, and which plants will run. Real time is the grid as found: a hotter afternoon, a plant tripping offline, or wind underdelivering shows up in the real-time price first. The spread is the market grading its own forecast, in dollars.

Is day-ahead usually higher?

Overnight hours often settle under their day-ahead price, and scarcity afternoons can blow through it by hundreds of dollars. The by-hour chart on this page shows the shape as it accumulates. Both markets can also clear negative.

Where does this data come from?

ERCOT's public MIS reports: day-ahead settlement point prices and real-time 15-minute settlement point prices for the eight load zones, the same feeds behind the prices page. On daylight-saving switch days the grid honestly shows 23 or 25 hours.

Live prices →The live dashboard →What is 4CP →What is the day-ahead market →