Looking ahead to Summer 2025 in North America

The Northern Hemisphere is a few days into Meteorological Spring and as temperatures gradually warm attention is shifting toward what conditions will be like this summer. A few signals are coming into view which may help to give an early look at what to expect.

Note that with all long-range forecasts, we are considering things generally over the course of the entire season. It is currently not possible to pick up on when or where specific events, such as heat waves, wildfires, and severe thunderstorm outbreaks will occur this far in advance. Rather, these forecasts consider how the season as a whole will compare to climatological norms.

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La Niña1 is on its way out. Over the past several weeks, the eastern third of the Equatorial Pacific has warmed to the point where the negative anomaly has disappeared. Temperatures in the middle third of the Equatorial Pacific remain below average.

After a late start and a relatively weak peak, La Niña forecasts were revised to show it ending during Spring or perhaps early-Summer 2025. ENSO-neutral conditions were observed during the Fall, which produced an unusually active Pacific Northwest storm season. Such is more or less normal during ENSO-neutral conditions.

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Ocean conditions

ENSO-neutral conditions are favored this summer but it appears the larger impact will be sea surface temperatures elsewhere in the Pacific Ocean. The North Pacific is significantly influential in North America because, in general, systems move from the Pacific eastward across the continent and into the Atlantic.

What we’re looking at as temperatures warm is a large area of above-average ocean temperatures between Hawaii and Alaska with below average temperatures from Baja to the region southeast of Hawaii. This pattern is very similar to 2022 and modeling suggests that it will continue through the summer months.

Looking beyond the North Pacific, global ocean temperatures continue to run well above average. The warming influence of the world’s oceans on many landmasses is likely to continue.

While temperatures have moderated slightly from the all-time records set in 2024, the global average of 21.03°C (69.85°F) on March 102 is well above the climatological norm of 20.52°C (68.94°F) for that date. Half a degree Celsius may not seem like a big difference, but note that within a normal year the global average sea surface temperature varies by about 0.3 to 0.4°C (0.5 to 0.7°F).

2022 as a proxy

It is reasonable to look at 2022 as a proxy for this summer as sea-surface temperatures in the North Pacific look similar to that year. Observations in Summer of 2022 showed nearly all of North America under above average temperatures.

Nunavut, Texas, the High Plains, and both California and Oregon had the strongest values above average. I expect much of North America will again be hot compared to average. That said, the exact location of where heat manifests itself may vary.

The Southwest monsoon was quite active in 2022 with a large area from El Paso toward Tonopah seeing much above average precipitation. The efficiency of the monsoon was driven by Great Basin heat that creates low pressure and pulls moisture from the Mexican Pacific Coast north into the Desert Southwest.

In August, heavy monsoon rainfall caused flash flooding in Death Valley National Park. This event caused debris flows that blocked roads and stranded over a thousand people in the park. Some of this monsoon moisture made it to the Inland Northwest for above average precipitation from Central Oregon to the Idaho Panhandle.

Atlantic hurricane season

Atlantic hurricane season runs from June 1 to November 30 with the most active period being August through October. The number of tropical storms and hurricanes that form in the Atlantic is determined by a number of factors, including sea-surface temperatures, ENSO, and the quantity of tropical waves3 entering the Atlantic from Africa.

ENSO-neutral conditions are a signal that the Atlantic hurricane season will not be extremely above average. In addition, while the Atlantic remains well above average sea-surface temperatures there are not as extreme as they were in 2024.

Above average water temperatures can lead to explosive hurricane growth, which was seen in a few storms during the 2024 season. The number of storms didn’t reach what was possible because tropical waves came off Africa further north.

Rather than running in the typical region through countries like Nigeria and Guinea, tropical waves tracked further north – possibly pulled by hot conditions along the Mediterranean. The result was that these waves emerged into cooler (but still above average) waters in the Atlantic and struggled to develop into tropical cyclones.

Modeling and data from 2022 suggest that this year’s wave track will be closer to the normal region but ENSO and (relatively) cooler water this summer makes it so the risk of explosive growth is less extreme.

Still, a near average season produces around seven hurricanes and regardless of whether or not a hurricane season is above average, if your home gets destroyed by a hurricane it’s a bad hurricane season for you. Spring and early Summer are the perfect time to prepare for people living from the Canadian Maritimes to the U.S. East Coast, along the Gulf of Mexico, and around the Caribbean.

Interestingly, the 2022 Atlantic hurricane season was quite calm for the Gulf of Mexico. I don’t know what sort of predictive value this offers for 2025 but readers should note that temperatures in the Gulf were somewhat closer to average that year than they are today.

Pacific Northwest wildfires

Oregon and Southern Idaho exhibit fairly healthy snowpack as we progress through March but the deep snowpack that was hoped for this winter in Washington and British Columbia did not materialize. This was largely the result of La Niña being later and weaker than forecast.

British Columbia snowpack was reported as 73% of average on March 1 with recent U.S. values ranging from 72% in the Puget Sound drainage to 124% in the Middle Snake drainage.4 Conditions improve the further south one goes.

Snowpack got a late start despite significant precipitation in November and December. The storm track was such that many storms came in from the Southwest, bringing warmer air up from the subtropical Pacific to keep snow levels high. Long dry stretches in January and February didn’t help.

A fairly wet and mild Spring is forecast in much of the Pacific Northwest. This is problematic for summer wildfires because wet and mild conditions allow for significant fuel growth. Once the region begins to dry in June, the newly grown brush will die off and be easy to light on fire.

Available data points toward this summer bringing above average temperatures to Washington, Oregon, Idaho, and British Columbia. Heat will speed up the dessication of Spring growth and by mid-Summer fuel load is probably going to be near critical conditions.

The vast majority of wildfires in the Contiguous United States are started by people, though dry lightning does play a role throughout the Northwest (including British Columbia).

Predicting exact wildfires is outside the scope of this article but general trends suggest the dry lightning threat may be strongest in arid regions in and around the Columbia Basin in June, the Blue Mountains, Northern Idaho, East Slopes of the Cascades, and Okanagan/Okanogan regions in July, and in the B.C. Interior in August.

Of course, predictability decreases as we look further into the future. These are just the favored regions based on both model data and previous similar years like 2022. A wildfire can form anywhere at any time and Pacific Northwest residents should be aware of their risk and prepared to evacuate with short notice during wildfire season.

Conclusions

Above average temperatures are favored for much of North America this Summer. The Great Lakes Region may be the exception, especially on the Canadian side, and a stronger than usual monsoon could moderate temperatures some in Arizona and New Mexico.

For the Pacific Northwest, above average temperatures don’t necessarily mean another heat dome on the magnitude of the June 2021 event is going to happen. Significant heat waves are possible any summer, and an above average summer does bring a greater chance of them, but I don’t think that risk is outstandingly high.

Wildfire season may be rough in Washington, Oregon, Idaho, and British Columbia. During the Meteorological Summer months of June, July, and August, this is more likely to be felt in inland regions.

Wildfires can happen throughout the region at any point during the dry season but areas west of the Cascades are climatologically more likely to be impacted in September. This is because cooling temperatures in the Canadian and Montana Rockies aid in switching the wind pattern to offshore, drying the western half of Washington and Oregon to increase fire risk.

This Atlantic hurricane season isn’t coming with a signal of being significantly above average. ENSO-neutral conditions favor near average tropical cyclone development but the wildcard there will be the impact of above average sea-surface temperatures.

1. La Niña and El Niño refer to sea surface temperatures in the Pacific Ocean near the equator. When La Niña is in place, these temperatures are below average whereas El Niño is the above average phase. This teleconnection is called the El Niño-Southern Oscillation, or ENSO, and when neither La Niña or El Niño are in place it is referred to as being ENSO Neutral. ↩︎
2. Using NOAA OISST values from 60°S to 60°N. ↩︎
3. A tropical wave is a low-pressure area that moves through the tropics, often bringing thunderstorms and increased moisture, and can sometimes develop into a tropical cyclone. ↩︎
4. The Middle Snake drainage is far Southeast Oregon and Southwest Idaho, including Boise. ↩︎