​An evening of low wind output on April 15 defined the month. A severe-thunderstorm system moved through the MISO footprint between the evening of April 14 and the night of April 15. MISO wind output fell from the April monthly evening average of around 15 GW to 7 GW on April 15.

With the wind fleet down and solar past peak generating hours, real-time prices at Indiana Hub hit $608/MWh during HE 18, more than 16 times the monthly Indiana Hub real-time average of $37.75/MWh. The day-ahead market priced the same hour at a fraction of that level.

Real-time top-bottom spreads expanded sharply at northern hubs. Indiana ($269/MW-day, up 46% year over year) and Michigan ($268/MW-day, up 58%) effectively tied at the top. Southern hubs went the other way: Arkansas four-hour real-time spreads fell 36% year over year and Texas dropped 44%. The north-south split, caused in part by transmission constraints, was similar to prior months.

Key takeaways

• MISO’s north-south TB4 gap hit its widest of the past year: Indiana real-time TB4s averaged $269/MW-day (up 46%) while Texas fell to $136/MW-day (down 44%).
• Michigan Hub posted the highest day-ahead average at $41/MWh, a $14/MWh premium over Arkansas at $27/MWh.
• MISO wind output dropped to 7 GW on April 15, less than half the monthly evening average, as a severe-thunderstorm system passed through.
• Natural gas grew to 21.5 GW (up 19% year over year) as coal fell to 16 GW (down 15%); solar averaged 5.3 GW (up 54%).
• Day-ahead regulation averaged $20/MWh, the highest-paying ancillary product for BESS in MISO.

An evening price spike on April 15 cleared 16x above Indiana hub’s monthly average

Spring shoulder months in MISO typically lack winter’s scarcity events. April 2026 broke that pattern between the evening of April 14 and the night of April 15.

A severe thunderstorm system set off tornadoes in southeast Michigan and altered wind patterns across the Lower Great Lakes. Therefore, wind generation was suppressed for roughly 24 hours.

MISO wind output fell to 7 GW on April 15, well below the April monthly evening average of around 15 GW. By 6 PM CPT, wind was 6.8 GW and solar had fallen from a 13.4 GW midday peak to 2.5 GW.

Gas units met the shortfall on top of normal evening ramping. Due to this ramp, real-time prices at Indiana Hub cleared $608/MWh, the highest hour of the month. By 8 PM the gap had closed and prices fell to $49/MWh. Wind recovered to its monthly average by April 17.

The day-ahead market had not priced the event. Day-ahead prices averaged $47/MWh across April 15, with the highest day-ahead hour clearing slightly above $80/MWh.

BESS that discharged in the day-ahead market captured roughly $50/MWh. BESS that held inventory for the real-time market captured more than $600/MWh during that single hour at Indiana, and over $570/MWh at Michigan.

Six other hours cleared above $200 in real-time across MISO during April, five concentrated in evening ramp windows on April 15-23 and two during early-morning tightness on April 20.

The supply stack in MISO shifted toward gas and solar

Natural gas averaged 21.5 GW in April 2026, up from 18.1 GW a year earlier. That 19% year-over-year increase filled the space left by coal.

Coal fell from 18.9 GW to 16.0 GW (down 15%). Solar grew the most in proportional terms, averaging 5.3 GW, a 54% increase that reflects new utility-scale solar across MISO. Wind rose 8% to 15.2 GW.

Solar peaked at 13.4 GW at midday on average, up more than 50% from the 8.7 GW peak in April 2025.

Average net load fell to 45.9 GW at 11 AM as solar maxed out, then climbed back to 61.1 GW by 7 PM, a swing of more than 15 GW compressed into eight hours.

The supply stack handled most of those ramps without incident, but April 15’s below-average wind and solar drop-off created scarcity for an hour.

MISO North hubs widened TB4 spreads as MISO South hubs compressed

Indiana Hub day-ahead prices averaged $39.5/MWh and real-time $38/MWh. Michigan posted the highest day-ahead average at $41/MWh, a $14/MWh premium over Arkansas at $27/MWh.

That price gap amplified into top-bottom spreads. Indiana Hub day-ahead four-hour top-bottom spreads averaged $165/MW-day (up 43% year over year), with real-time at $269/MW-day (up 46%).

Additionally, Michigan and Illinois followed similar trajectories. Both widened on the day-ahead side and widened more on the real-time side.

The southern zones did not follow this trend. Arkansas day-ahead TB4 spreads were essentially flat year over year at $113/MW-day (up 8%), but real-time fell 36% to $133/MW-day.

Texas day-ahead TB4s dropped 24% to $118/MW-day and real-time TB4s fell 44% to $136/MW-day. Additionally, Louisiana real-time TB4s fell 21%.

The north-south gap for real-time TB4s reached more than $130/MW-day between Indiana and Texas in April, the widest of any monthly benchmark in the past year.

The pattern reflects denser industrial load and limited import paths in MISO North against surplus natural gas capacity in MISO South. Constrained transfer capability between the two regions amplifies the gap whenever northern supply tightens.

For a 100 MW / 400 MWh battery operating in the real-time market, the gap between Indiana and Texas was roughly $13,300/day in April, or about $400,000 over the month.

Regulation again paid more than reserves

Day-ahead regulation averaged $20/MWh, up 15% year over year, holding its position as the highest-value ancillary product for BESS in MISO. Real-time regulation cleared $20/MWh, down 7% YoY.

Day-ahead spinning reserve averaged $3/MWh, down 44% year over year. Real-time spinning reserve averaged $2/MWh.

The MISO ancillary stack stays regulation-led for BESS operators. The gap widened further in April: regulation cleared more than 7 times the price of day-ahead spinning reserve, versus roughly 3.5 times in April 2025.

Capacity committed to spinning or supplemental reserve missed both the higher regulation clearings and the April 15 evening ramp.

Outlook

The April 15 evening ramp was the defining event of the month. A single severe-weather system suppressed MISO wind for 24 hours, and the resulting 8 to 10 GW gap tightened the system.

Losing a third of the wind fleet for a day is an event the gas stack cannot fully absorb during the evening ramp. In the shoulder season, that ramp shape (not winter scarcity) becomes the dominant spread driver.

Northern hubs continue to outperform. Real-time four-hour top-bottom spreads in Indiana, Michigan, and Illinois all sat more than $90/MW-day above their southern counterparts, a wider gap than March. Transfer constraints, denser industrial load, and thinner northern reserve margins will not resolve in the next quarter.

For operators, April reinforced that real-time dispatch captured what day-ahead missed, and that initial site selection defines revenue potential.