An El Niño Summer is Coming: Expected Impacts for the US
As the United States spring approaches, so are the warmer, summer months. Last year summer was dreadful with extreme temperatures and harsh weather, but this year is expected to be better. El Niño, a natural climatic phenomenon, nearly always warmer the waters in the mid region of the Pacific, caused higher than the normal temperatures. While this year is expected to be the same as last with no drop during the summer, this year’s peak El Niño is expected to wear off significantly, so it will be absent by summer time.
However, the phasing off of El Niño is not going to help as much as people expect it to. Weather experts and climatologists are warning that the absence of El Niño is going to be much to take heed of. Without the drop in spring, the unregulated higher temperature caused by human activity is going to be a huge factor.
Defining El Niño, La Niña, and Neutral Phases
El Niño and La Niña are both parts of a cycle known as El Niño-Southern Oscillation (ENSO). This cycle naturally occurs and impacts the climate of the entire world, affecting the weather of different countries. El Niño occurs as a result of warm ocean surface temperatures in the eastern and central Pacific. On the other hand, La Niña has colder ocean surface temperatures than normal. The neutral phase is reached when ocean temperatures are close to the expected average.
The NOAA Climate Prediction Center has said that in the equatorial Pacific, ocean temperatures will average out by June 2025, signaling the start of a neutral phase. El Niño conditions will influence oceanic and atmospheric conditions in the spring, and by early summer, La Niña conditions are expected to strengthen.
The continental United States is impacted differently by these phases during different seasons. The primary impact is during the winter due to the much stronger temperature differences and the way these interact with the North American jet stream and where the storm systems travel. During summer, these differences are not as pronounced and the effects are much less direct and more complicated.
Historical Context: Heat Without El Niño
When trying to forecast the impacts of a neutral or transitioning ENSO summer, researchers start with historical analogs. Here are two notable examples:
- Summer, 2016: Following a very strong El Niño winter, La Niña conditions set in by mid-summer. This helped create one of the hottest summers on record for the contiguous United States.
- Summer, 2020: A weak El Niño winter, then a La Niña shift by mid-summer. This super hot summer with moderate ENSO conditions also marked a record hot summer for the U.S. This summer also saw the most active hurricane season in history for the Atlantic.
These examples highlight a critical point, which is that El Niño is not the only factor that defines the summer heat in the United States. An increase in the average temperature due to climate change means the effects of natural variability would increase as well. As Michelle L’Heureux, a climate scientist with NOAA’s Climate Prediction Center, states, “This obviously isn’t our grandmother’s transition out of El Niño. We’re in a much warmer world so the impacts will be different. We’re seeing the consequences of climate change.”
Temperature Predictions for Summer 2025
Looking at summer temperature forecasts, most of the lower 48 states are expected to experience above-average mean temperature, with the exception of small areas in the Dakotas, Montana, and Minnesota which are expected to have an equal chance of below, near and above normal seasonal temperature.
According to the data, most of the Western region is likely to experience an increase in temperature, consistent with the rate of increase in temperature over previous years. NOAA has data showing that the West has experienced the most significant increase in summer temperatures over the past 30 years compared to any other region in the United States. A good example is Phoenix, Arizona, which has recently experienced a surge in temperatures. Last July the city recorded a historical average temperature of 102.7°F. Last year also marked the deadliest year on record for heat-related fatalities in Maricopa County.
In the West, the rural and agricultural communities deal with unique issues, facing the threat of heat-stressed livestock that impacts food security, along with heightened irrigation demands and crop strain due to increased evapotranspiration.
Drought and Precipitation Risks
The Western and central United States are forecasted to have drier-than-normal conditions come early to mid-summer 2025, and with the added warmth, these areas are likely to face worsening drought conditions. Areas where dryness and heat are compounding, as well as areas with increased wildfire exposure, will face significant strain on water resources; not to mention the potential negative impacts facing agricultural and energy systems.
In contrast, the Northeast and Gulf Coast are anticipating the opposite—I mean, come on, right? Areas in the Northeast could have flooding, with the potential of fuel from tropical storms further complicating precipitation patterns.
The Atlantic Hurricane Outlook
A hyperactive Atlantic hurricane season is likely to emerge, all from record ocean temperatures being sustained for over a year, compounded with warming La Niña conditions. La Niña usually creates favorable atmospheric conditions for the development of hurricanes by providing weaker vertical wind shear, which allows storms to form, strengthen, and persist in the Atlantic basin. Moreover, warm sea surface temperatures offer the energy needed to drive tropical cyclones.
Not long ago, forecasters at Colorado State University issued what is, in their own words, the earliest-ever forecast for the Atlantic hurricane season. They expect a far-above-average number of major hurricanes to impact the U.S. coastline and the Caribbean. These types of predictions highlight the increased frequency of other storm-related hazards such as wind destruction, storm surge, and flooding in the interior regions.
Heat and Public Health
Heat endangers the public directly, in addition to threatening the infrastructure and ecosystems. There are vulnerable groups such as the elderly, children, outdoor workers, and people with chronic illnesses. These groups are at a heightened risk of heat-related illnesses such as heat exhaustion, heatstroke, and even heart diseases.
The urban heat island effect also impacts the public negatively. Places with lots of concrete and a small quantity of nature can suffer intensified temperatures. These regions are particularly hard hit by extreme summer heat, and with the addition of U.S. Western cities, require the establishment of emergency centers and public hydration advisories.
Rural communities face additional challenges, especially in areas where agricultural workers labor under harsh, hot conditions. Productivity reduction and heat exhaustion are both severe in hot conditions.
Agricultural and Ecosystem Effects
Increased temperatures and changes in rainfall will impact ecosystems and agricultural activities. Some crops may become more challenging. For example, extreme temperatures during critical stages of growth can adversely impact heat-sensitive crops like corn, wheat, and soybeans. Productivity among livestock may also decline because of thermal stress.
These factors contribute to increased forest and grassland wildfires, as well as rural community wildfires. For many years, and most recently in California, Colorado, Oregon, and other Western regions, hot and dry summers have been contributors to record-breaking wildfires.
High temperatures also impact water through evaporation, directly increasing stress levels in fish. An extended period of reduced water intake can result in tree dieback. Without trees, forests become more susceptible to pest infestations as well as infestation and dieback.
The Past and Climate Change
Looking back at history helps predict risks for this summer. Climate change has continuously raised the “average temperature,” allowing extreme heat to be more and more common. Every summer observed in the United States and globally, is hotter every year than the previous year, making summers more “average.”
Severe weather, or heat waves are forecasted to last longer, reach more diverse areas, and be more intense, making the ongoing climate shift more challenging to adapt to. The range of areas affected is projected to broaden which will strain adaptation and emergency response efforts.
El Niño Free Summer
Strategy adaptations help forecast the risks with this summer’s sizzling heat and the potential for hurricanes. These are:
- Urban adaptation: Introduction of more parks and greenery, installation of heat reflecting roofs, and urban cooling or heat reducing centers aid in tackling the increase of heat in the areas within the city.
- Water management: Agriculture and fire suppression strategies now have access to additional resources needed for agriculture, and during drought, water supply for drinking is managed.
- Healthcare strategies: Helping individuals to identify the more moderate, early symptoms of heat-related sickness, hydrating and emphasizing the importance of heat safety helps to educate the public.
- Resilient facilities: Over and under the extreme weather, power grids, transportation links, and systems for emergency response and storm evaluation are fortified for the upcoming climate.
- Using more resilient crop varieties, better irrigation practices, and modifying timelines for planting are important changes in agriculture.
To control the frequency and intensity of extreme weather, like droughts and floods, it is crucial to reduce greenhouse gas emissions.
Looking Ahead: The Climate Outlook for Summer Weather
The summer serves as a reminder of a greater reality, even if El Niño disappears, extreme weather is still likely to persist. It is, therefore, of higher importance to study the interaction between climate change and natural climate variability.
With La Niña patterns strengthening in the Atlantic alongside record ocean temperatures, the U.S. is poised for a summer of heat waves, droughts, wildfires, and even an active hurricane season. There is an ever-increasing demand for adapting to the new and rapidly changing conditions.
As Michelle L’Heureux puts it, “This summer is a vivid reminder that climate change is rewriting the rules. Even as ENSO transitions toward neutral or La Niña, the underlying warming trend and increase in frequency of weather and climate extremes, the reality is we are living in a new climate reality.”
Key Takeaways
- The expectation is for El Niño to dissipate by the start of summer, giving way to neutral conditions or La Niña phases.
- Above-normal temperatures are forecast for most of the Lower 48, West is expected to see the most extreme heat.
- Drying conditions in the West and Central areas of the US might worsen existing drought conditions and increase wildfire threats.
- In the East from the Gulf of Mexico and the Northeastern parts, wetter conditions might intensify flooding and increase storm activity.
- The Atlantic hurricane season is expected to be very active and bring in a major storm.
- The heat, wildfires, drought and hurricanes bring destruction to the human health, and the ecosystem.
- Plans for urban development, water management, agriculture, and public health requires better planning.
In conclusion, it seems like the expected summer for 2025 would be an extreme summer without El Niño, extreme events seem very likely. We have to realize that lack of a familiar climate pattern does not guarantee safety. Increased temperatures, record hot oceans and the ever present climate changes will ensure a hot summer remains a huge threat to the US.
