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 26 · CT · 8-zone average- - day-ahead — real-time
$10$49$87$125$16412 AM6 AM12 PM6 PM11 PM
Spread by hour (RT − DA)12 AM: −$0.801 AM: +$0.592 AM: +$8.263 AM: +$16.744 AM: +$21.145 AM: +$23.716 AM: +$20.907 AM: +$31.878 AM: +$12.829 AM: +$13.2810 AM: +$15.1911 AM: +$17.4412 PM: +$18.221 PM: +$28.392 PM: +$52.51

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
$51.50
real-time average vs $32.81 day-ahead
Settled under day-ahead
56%
of 505 hours since 2026-07-27
Biggest miss of the window
+$274.59
Aug 23 9:00 PM CT: priced $56.09, settled $330.69
Tomorrow's prices
$27.72–$105.14
tomorrow's day-ahead range, cheapest to priciest hour

The premium by hour

average spread by hour
+$10−$1012AM: +$1.26 over 22 hours1AM: +$1.04 over 22 hours2AM: +$1.41 over 21 hours3AM: +$1.76 over 21 hours4AM: +$1.98 over 21 hours5AM: +$2.90 over 21 hours6AM: +$2.75 over 21 hours7AM: +$2.97 over 21 hours8AM: +$1.55 over 21 hours9AM: +$2.21 over 21 hours10AM: +$1.51 over 21 hours11AM: −$0.74 over 21 hours12PM: −$0.25 over 21 hours1PM: +$2.28 over 21 hours2PM: −$0.46 over 20 hours3PM: −$2.87 over 21 hours4PM: −$4.64 over 21 hours5PM: −$0.61 over 21 hours6PM: −$6.32 over 21 hours7PM: −$10.38 over 21 hours8PM: −$7.39 over 21 hours9PM: −$1.14 over 21 hours10PM: −$5.73 over 21 hours11PM: +$4.90 over 21 hours12AM6AM12PM6PM

Average of 505 paired hours since 2026-07-27. 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
$33$10012 AM12 PM11 PM$105.14

Aug 27, as the day-ahead market cleared it. Real time starts grading at midnight.

Today by zone

day-ahead vs real-time averages
ZoneDay-ahead avgReal-time avgSpread
AEN (Austin Energy)$56.49$43.82+$11.51
CPS (San Antonio)$57.63$46.46+$13.97
Houston$53.75$41.22+$10.05
LCRA$63.32$67.62+$31.95
North (DFW)$58.40$46.56+$15.63
Rayburn$57.46$44.60+$14.04
South$55.40$62.57+$27.99
West$60.61$59.12+$24.32

Real-time averages cover graded hours only. Full interval detail is on the prices page.

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 →