Anacostia River at sunrise, May 8, 2015 ( Jim Havard via Flickr )

Last Sunday, when we hit a high of 84 in Washington, D.C., we turned on the summer switch and it’s staying on.  It may dim for a brief period or two but summer weather is mostly here to stay.

In our future, we foresee the majority of our days reaching 80 or higher and no days in which we don’t at least reach the low 70s.* The threat of a frost or freeze is history and you can safely store your winter coats.

Look at the average forecast high and low temperature for the next 16 days from the group of simulations making up the GFS model ensemble:


High and low temperature forecast for the next 16 days from the Global Ensemble Forecast System (WeatherBell.com)

With the exception of Wednesday-Saturday next week, when forecast highs range from 74-79, every day is forecast to be 80 or higher.  Recall, we’ve already had 6 days in a row of 80 or higher since last Sunday (if we include today). We’ll very likely tack on four more 80+ days through next Tuesday – assembling a remarkable 10-day streak of 80+ days – the longest on record (dating back to 1871) for the first half of May in D.C.

We may even introduce some 90 degree days into the mix. Capital Weather Gang’s Matt Rogers, who specializes in long-range forecasting, sees three opportunities for 90-degree weather in the next 2-3 weeks.  “I think Tuesday we could be in the low 90s, during the May 18-20 period we could see some 90s, and we’ll have a third chance around or just after the Memorial Day weekend,” Rogers said.

The average date of D.C.’s first 90 degree day is May 18 and we should be about a week ahead of that given the forecast for temperatures near or above 90 Monday and/or Tuesday next week.  But we’ll be nowhere close to the earliest 90+ day on record which occurred March 22, 1907.

The weather responsible for all of this summer warmth so soon is a persistent ridge in the jet stream over the eastern U.S. which has allowed a heat dome to become established.  Models forecast it to be a persistent feature through the balance of May.


High altitude weather pattern forecast for this Sunday showing warm jet stream ridge over eastern U.S. (WeatherBell.com)

What’s amazing is that it seems like just the other day we were pronouncing winter over.  In fact, it was March 30 when we declared winter dead.

[We pronounce winter over, effective today – March 30, in Washington, D.C. area]

In all, spring (by our definition) in D.C. lasted about 35 days – essentially comprising the month of April.


Dawn, April 18, 2015 ( Jim Knapp via Flickr )

Rest in peace.

* We’re defining the start of summer as the point at which we no longer see potential for two or more straight days with highs below 70 degrees and the forecast calls for the majority of days to reach at least 80 in the weeks to come.