El Niño Summer Forecast: How Hot And Stormy Will It Be In IL?

Developing El Niño conditions could make it a stormy and extremely hot summer in Illinois, according to a new forecast.

The private weather company AccuWeather said the developing climate pattern is expected to bring building heat, rounds of severe weather, and shifting regional patterns across the United States.

Driven by warming ocean waters in the Pacific, the El Niño is likely to strengthen through the summer, influencing temperatures, storm tracks and hurricane activity, AccuWeather said.

In Illinois, AccuWeather is predicting the number of 90-degree days in Chicago will be near or above the historical average, with the same predicted in Boston, New York City and Philadelphia. Chicago recorded 27 days that reached 90+ degrees in 2025. In 2026, it's predicted to see between 16 and 24.

Severe weather is expected to be most active from early to midsummer across the Midwest, Plains and Ohio Valley.

In July and August, Illinois is seen as at "high" risk of destructive lines of thunderstorms known as derechos. A derecho is much more powerful than a typical thunderstorm and is sometimes called an “inland hurricane” because of the widespread wind damage it can cause.

If you’re traveling this summer, here’s what to expect in the rest of the country:

In the Northeast and mid-Atlantic, including parts of New York and Pennsylvania, the summer is expected to trend warmer than average overall, with periodic stretches of intense heat. Thunderstorms could bring localized flooding, but longer dry spells are also possible as storm tracks shift.

Across the South and Southeast, frequent thunderstorms and above-average rainfall are expected at times, especially as moisture increases later in the season. However, heat and humidity will still build between storm systems.

In the West, especially the Southwest, hot and dry conditions are expected to dominate, raising concerns about drought and wildfire risk as the summer progresses.

The emerging El Niño may also influence the Atlantic hurricane season, which is expected to be near or slightly below average overall due to wind patterns that can disrupt storm formation.

Still, forecasters caution that even a quieter season can produce dangerous storms, and that impacts can vary widely by region.

Globally, scientists say El Niño conditions are likely to develop between late spring and summer, increasing the chances of extreme weather, including heavier rainfall in parts of North America and higher overall temperatures.

AccuWeather meteorologists say the evolving pattern will become more influential as summer progresses, meaning conditions later in the season could look markedly different from early summer.