Key Takeaways
- Most of the United States will experience a cooler‑than‑normal May, especially the Midwest and eastern half.
- Overnight lows may dip into the 40s and even frost/freeze in parts of the Midwest and Great Lakes region.
- The West Coast, particularly the Pacific Northwest, is already warming and will see temperatures well above average early in the month.
- A weakening jet‑stream trough and reduced atmospheric blocking will allow warmer air to shift eastward after the third week of May.
- The Climate Prediction Center expects overall summer (May‑July) temperatures to be above normal for the majority of the country, with pronounced regional extremes.
Early‑Season Cool Snap Across the Nation
Meteorologists are highlighting an unusually cool pattern that will dominate much of the United States throughout much of May. After an unpredictable spring with frequent temperature swings, the Climate Prediction Center’s forecaster Brad Pugh notes that the Midwest will feel the brunt of the chill, with some overnight lows potentially reaching freezing or near‑freezing levels. For the eastern half of the country, the first half of May is expected to resemble early spring more than typical early‑May weather, featuring many cloudy days and only intermittent sunshine. Residents should therefore keep layers handy, as temperatures will often feel more akin to late March or early April than to the onset of May.
Cold Air Pool Over the Midwest and Great Lakes
The cool conditions are being driven by a persistent dip in the jet stream that is “lingering” over the United States, according to Paul Pastelok, AccuWeather’s lead long‑range expert. This dip is reinforced by atmospheric blocking that prevents the colder air from moving northward into Canada. As a result, states surrounding the Great Lakes and the Upper Mississippi Valley may see temperatures 5 to 10 degrees below normal during the first week of May, with early‑morning lows already hitting the freezing point in places like Wisconsin. Frost or freeze events could re‑occur around May 7‑8, and similar chilly overnight readings are possible across the Mid‑Atlantic and New England.
Temperatures Below Normal in Major Cities
Specific metropolitan areas are expected to record notable departures from average temperatures. New York City, for example, usually sees highs climb from the upper 60s early in May to the mid‑70s later in the month; this year, highs are likely to linger in the 60s or even the upper 50s, with lows dropping into the 40s. Chicago’s typical May highs of the 60s to mid‑70s will be replaced by readings 10 to 15 degrees lower during the first part of the month, keeping daytime temperatures in the 50s. By mid‑month, however, the warming trend moving westward will reach Chicago, bringing temperatures back toward or above normal.
Rapid Warm‑Up on the West Coast
While much of the country wrestles with cooler air, the Pacific Northwest is already heating up quickly. Cities such as Spokane, Washington, are forecast to hit highs of 80 °F on May 3 and 79 °F on May 4, with temperatures climbing into the 70s and even low 80s across the Great Basin and as far south as California by the end of the month. This early surge of warmth means residents should begin transitioning to summer wardrobes sooner rather than later, and many daily temperature records are at risk of being broken as the season progresses.
Transition From Cool to Warm: The Third‑Week Shift Pastelok explains that the blocking pattern that has kept cool air entrenched over the eastern United States will weaken by the third week of May. When this occurs, the cooler air will retreat, allowing a warmer flow to move eastward across the country. This transition will be most noticeable in the Midwest and Northeast, where temperatures will gradually climb toward more typical May values and then into early June. While the western regions experience an earlier and more rapid warming, the eastern shift will be slower, meaning that summer‑like heat and humidity may not fully arrive until later in June.
Projected Summer Outlook: Above‑Normal Heat With Regional Extremes
The Climate Prediction Center’s three‑month outlook (May‑July) indicates that temperature probabilities lean above normal for the majority of the United States. Areas in the Northwest, parts of the South, and the Mid‑Atlantic are expected to have the highest chances of experiencing above‑average warmth. AccuWeather’s forecast reinforces this, calling for a “summer of weather extremes” that includes heat waves in the West and South, repeated thunderstorm complexes that threaten flash flooding from Texas to the Ohio Valley, and worsening drought conditions in the Northwest and Great Basin. As a result, the nation may see dramatically divergent weather conditions simultaneously—flooding in one region while neighboring areas endure extreme heat or drought.
Implications for Outdoor Activities and Agriculture
The cooler May temperatures and potential frosts could have significant implications for agriculture, especially for crops that are sensitive to early‑season frost. Farmers in the Midwest and Great Lakes regions should be prepared for a later planting window and may need to protect vulnerable seedlings. Conversely, the early heat surge in the Northwest could accelerate irrigation demands and increase fire risk, as rapid drying of vegetation creates favorable conditions for wildfires. For the general public, the cooler start to May may extend the season for activities such as bonfires and evening gatherings, while also delaying the opening of outdoor swimming pools until later in June.
Seasonal Planning Advice
Given the forecasted temperature swings, individuals and communities are advised to stay flexible with their seasonal plans. Layered clothing will be essential for early May, especially in the eastern and central states, while early‑season frost warnings should prompt protective actions for pets, plants, and outdoor equipment. As the warming front moves eastward, residents should begin transitioning to summer attire and prepare for potentially high temperatures in the West, which may bring with them increased risk of heat‑related health issues and heightened fire danger. Monitoring local forecasts and heat‑related advisories will be crucial throughout the transition period.
Conclusion
Overall, May 2026 is shaping up to be a month of contrasts: a cool, sometimes unsettled start for much of the United States, followed by a swift and pronounced warming trend in the West, and a gradual but steady move toward summer heat across the entire nation. The Climate Prediction Center’s summer outlook suggests that above‑normal temperatures will dominate, but the timing and intensity of that heat will vary widely by region. Staying informed about these shifting patterns will help people plan responsibly for everything from farming and recreation to energy use and safety.