It’s unanimous. Washington is in for another hot summer, forecasters say.
While the final touches are still being put on Capital Weather Gang’s forecast set for release next week, we examined the outlooks from five separate forecasting groups, which include the National Weather Service and four companies from the private sector. All of them lean toward steamier-than-normal conditions.
A hotter-than-normal summer would be nothing new. Incredibly, the last eight summers (2010 to 2017) have been hotter than the 1981 to 2010 average and include four of the five hottest on record.
While forecasters lean toward a toasty summer, they are generally not calling for a record-setter. Weather models tend to project moderate rather than extreme warmth.
All of the forecasters we interviewed are calling for 35 to 42 days with highs at or above 90 degrees (including the four to date), which is close to the average of 36 or slightly above.
Whether El Niño starts to develop is a big wild card in the outlook. El Niño, which refers to the episodic warming of the eastern and central tropical Pacific Ocean, tends to favor cooler summer conditions in our region. Some models suggest that El Niño may start to form late this summer, which would tend to bring relief from the heat by August.
Below, find the details of what forecasters are predicting …
AccuWeather: Paul Pastelok
- Temperature forecast: normal to slightly above normal (by 0 to 1 degrees)
- Precipitation forecast: above normal (130 percent of normal)
- Number of 90-degree days: 35
Paul Pastelok, long-range forecasting specialist at AccuWeather, says to expect a “little bit of everything” this summer. He foresees “strong thunderstorm potential in June and July, some dry periods, and back-and-forth cool-downs and warm-ups.”
In August and September, Pastelok says, the Carolinas could be in a vulnerable position for tropical storm threats, but it’s unclear whether the moisture will come up into the Washington area and, if so, how heavily.
Don’t be surprised if temperatures end up a little higher than predicted. “Warm surges in May have been very impressive, outdoing the cooler periods,” he said.
Commodity Weather Group: Matt Rogers
- Temperature forecast: slightly above normal (by 1 degree)
- Precipitation forecast: near normal
- Number of 90-plus-degree days: 40
Matt Rogers, Commodity Weather Group chief executive, says summer will get off to a hot start but will cool toward the second half because of the influence of El Niño.
“If that transition to El Niño runs faster, we could slip into a cooler than normal summer, and, if slower, then it could go slightly hotter,” Rogers says. “We are not expecting a major hot summer, though, thanks to the configuration of water temperatures in the north and eastern Pacific.”
(Matt Rogers is also a regular contributor to Capital Weather Gang.)
WeatherBell Analytics: Joe Bastardi
- Temperature forecast: slightly above normal (by 0.5 degrees)
- Number of 90-plus-degree days: 40
On his blog (behind a paywall), WeatherBell Analytics chief forecaster Joe Bastardi writes: “I don’t think there will be much cool air around.” He’s calling for the season’s hottest weather early in the season, emanating from Southern Plains. Like Rogers, he predicts the hot weather will wane later in the summer because of the possible development of El Niño.
The Weather Company: Todd Crawford
- Temperature forecast: slightly above normal (by 0.9 degrees)
- Number of 90-plus-degree days: 42
While the other forecasters have placed emphasis on the effects of El Niño on the summer outlook, Todd Crawford, senior meteorologist for the Weather Company, says conditions in the Arctic may also play a significant role in how the summer here plays out.
He says the lack of Arctic ice has probably contributed to the “historically hot” summer patterns in our region in recent years. As Arctic sea ice is abnormally low this year, that would tend to favor a hot summer yet again.
But Crawford cautions that the relationship between Arctic ice and summer temperatures may not work this year because of the weird behavior of the polar vortex since the spring, which could exert a cooling influence into the summer. Like Rogers and Bastardi, he says a developing El Niño could then cool things down late in the summer.
National Weather Service: Stephen Baxter
- Temperature forecast: leans slightly above normal (by about 0.25 degrees)
- Precipitation forecast: leans above normal
The National Weather Service’s generalized maps published online, which characterize how it expects temperatures and precipitation will compare to normal, suggest that it slightly favors a warm and wet summer.
But Stephen Baxter, a meteorologist at its Climate Prediction Center, explained that its forecast for the Washington area is slightly cooler than the average of the last 15 summers. Recent summers have been so warm that even “above normal” temperatures (relative to the last 30 years) are lower than recent years.
Baxter agrees that the possibility of a nascent El Niño could start to cool things down by July, August or September. He also says that ocean temperature patterns in both the Atlantic and Pacific “point on the cooler side.”