Why is it so cold? Temps down to 30 below normal. See lows near you

• A strong cold front is bringing a widespread drop in temperatures across the central and eastern United States.
• The cooler weather is caused by a dip in the jet stream allowing Canadian air to move south.
• Some Southern states may experience record-low maximum temperatures, with highs 20 to 30 degrees below average.
• Long-range forecasts suggest below-normal temperatures will likely continue into mid-May for much of the central and eastern U.S.

A strong cold front is sweeping across the United States, delivering a widespread and noticeable drop in temperatures from the Plains to the East. The system is bringing a sharp break from recent conditions, with cooler air expanding across much of the central and eastern U.S. as the week progresses.

The change is being driven by a deep dip in the jet stream, which is allowing a surge of cooler air to move south out of Canada. As the jet stream bends, it helps funnel that air mass into the Plains and Mississippi Valley, then spreads it eastward behind a broad storm system tracking across the country.

That storm system is doing more than just pushing the front through — it is helping reinforce the cooler pattern. Strong low pressure is pulling in northerly winds on its backside while spreading clouds and rain ahead of it, limiting daytime warming and helping the cooler air linger in place.

The result is a stretch of below-average temperatures across much of the eastern two-thirds of the country, with a noticeable step-down in conditions compared to earlier in the week. The coldest air remains focused across the northern tier, but the influence of this system extends well into the South as the front continues to move and stall near the Gulf Coast, bringing well below-average temperatures to those states.

"Some record low maximum temperatures may be set in the Southern states, with highs in the 40s and 50s F in some locations, compared to historical averages in the 70s to near 80," AccuWeather Meteorologist Brandon Buckingham said. "That's 20 to 30 degrees below average."

How cold will temperatures get?

In the West, the Pacific Northwest is expected to dip into the mid-40s before recovering into the low 50s. California follows a similar pattern, with coastal areas in the upper 40s rising into the mid-50s, the Central Valley holding in the low to mid-50s, and Southern California climbing from the upper 50s into the mid-60s.

The Great Basin and Rockies remain the coldest part of the region, with overnight lows in the mid-20s to mid-30s, though a slight warming trend is expected inland on the second night. Farther north, the Northern Rockies and Northern Plains stay cold but show minor moderation. Montana, Wyoming and the Dakotas hold in the mid-20s to low 30s on Night 1, warming slightly into the upper 20s and mid-30s by the following night.

Across the Midwest, temperatures remain seasonably cool. The Upper Midwest, including Minnesota, Wisconsin and Michigan, stays in the upper 20s to mid-30s both Thursday and Friday evenings, April 30 and May 1. Farther south into Illinois, Indiana and Ohio, lows range from the mid-30s to mid-40s, with a slight warming trend toward the second night, especially in the Ohio Valley.

The Central and Southern Plains see more noticeable warming. Kansas and Oklahoma move from the upper 30s into the mid-40s, while Texas shows a clear north-to-south gradient. North Texas holds in the low to mid-40s, Central Texas rises from the upper 40s into the mid-50s, and South Texas stays much milder, ranging from the 60s into the low 70s.

In the Southwest, Arizona and New Mexico also trend warmer, with overnight lows climbing from the 40s into the 50s and locally into the 60s in desert areas.

The Southeast remains mild overall. Tennessee and the Carolinas range from the mid-40s to mid-50s between nights, while Georgia and Alabama stay in the upper 40s to upper 50s. Florida remains the warmest region in the East, with North Florida rising into the 60s and South Florida holding in the 70s and approaching 80 degrees.

The Northeast and Mid-Atlantic stay the coolest in the East, with New England dipping into the upper 20s to mid-30s and the Mid-Atlantic holding in the mid-30s to mid-40s. A slight warming trend is expected, but conditions remain cool overall.

Why is it so cold?

This round of cold air is being driven by a strong dip in the jet stream, which is allowing a surge of colder, Canadian-origin air to spill south across the central and eastern United States, according to the Weather Prediction Center.

At the same time, a large, slow-moving storm system is riding along that jet stream dip. Instead of a quick shot of cold air, this setup spreads cooler temperatures over a much broader area and keeps them in place longer. That is why places like Texas, the Midwest and the East are all seeing a noticeable drop at the same time.

The system is also pulling in widespread cloud cover and bands of rain and thunderstorms, especially from Texas into the Ohio Valley and Southeast. Those clouds act like a lid on daytime warming, limiting how much temperatures can recover even in the afternoon.

Behind the front, wind flow is shifting out of the north and northeast, reinforcing the cooler air mass. In areas where rain is ongoing — including parts of Texas and the Lower Mississippi Valley — evaporative cooling is also helping drag temperatures down further.

In short, this is not just a quick cold snap. It is a broad, jet-stream-driven pattern change that is spreading cooler air across much of the country while storm systems help lock it in for several days.

When will temperatures warm back up?

Temperatures are not expected to stay in a true cold snap pattern, but the broader setup favors a slower return to spring warmth for much of the country, according to data from the Climate Prediction Center.

Long-range outlooks covering early to mid-May continue to signal below-normal temperatures across a large portion of the central and eastern U.S. That does not necessarily mean persistent cold or freezing conditions, but rather readings that trend cooler than what is typical for this time of year. In many areas, that can translate to daytime highs running roughly 5 to 15 degrees below average at times, especially in the Plains and Midwest.

"Below normal temperatures are favored for an area from most of the Great Plains, excluding Texas, eastward across the Great Lakes, Ohio and Tennessee Valleys, to the Northeast and Mid-Atlantic," the Climate Prediction Center wrote in the long-range outlook. "Probabilities exceed 40 percent over much of the northern central CONUS, where model temperature tools agree on persistent below normal temperatures. Lower probabilities favoring below normal temperatures are predicted over the Mid-Atlantic and Northeast, where some temperature tools predict rising temperatures in week 4."

The pattern behind this cooler stretch is tied to a more active jet stream, with repeated dips allowing cooler air to reload into the central and eastern states rather than a quick transition to steady spring warmth. Between systems, there will still be milder days, but they may be interrupted by additional reinforcing fronts.

Farther west and toward parts of the South, warmer conditions are more likely to build in at times, but even there the signal is not uniform or locked in. Overall, the expectation is for a gradual, uneven warm-up rather than a sustained shift into consistently above-normal temperatures through mid-May.

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Brandi D. Addison covers weather across the United States as the Weather Connect Reporter for the USA TODAY Network. She can be reached at [email protected]. Find her on Facebook here.