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For the second time in a week, activists will take to the streets of Washington, D.C., and hundreds of other locations worldwide. This time, the issue at hand will be global warming, and the backdrop in the nation's capital on Saturday could not be more appropriate.

The weather forecast for Washington calls for potentially record-shattering, summer-like heat, with highs near or just above 90 degrees Fahrenheit, and heat indices -- the combination of air temperature and dew point measurements -- in the upper 90s. This is more typical for June and July in Washington than April.

SEE ALSO:In ultimate insult, Trump rolls back EPA's climate policies from within the EPA

While the possibly record setting heat will make those participating in the march feel uncomfortable at times, it will also provide a photogenic backdrop for the event.

The march, which was being organized regardless of who had won the presidency in November, is now aimed squarely at the Trump administration and its outright rejection of mainstream climate science findings and reversals of years of progress on reducing greenhouse gas.

Unlike the March for Science a week earlier, in which scientists from various disciplines came out in droves to demand to be heard during the first-of-its-kind protest, the climate movement is already a force to be reckoned with when it comes to politics. The first such march, in 2009, drew 400,000 participants in New York alone.

Forecast high temperatures for April 29, 2017, with record highs circled.Credit: weatherbell analytics

Climate groups such as 350.org were instrumental in convincing former president Barack Obama to reject the approval of the Keystone XL Pipeline, though that decision has since been reversed under Trump.

The march will have some star power, as Richard Branson, the U.K.-based business mogul and friend of Obama, announced his participation on Friday during a discussion with the Washington Post.

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“I’ve only marched twice in my life so far," Branson said, citing his participation in anti-Vietnam and Iraq War demonstrations.

"And climate change is the third time, and just as important, I think, for the world as those other two, and just as important for our grandchildren and great-grandchildren.”

Former vice president Al Gore, actor and activist Leonardo DiCaprio and other noteworthy figures active in the climate movement are also expected to participate.

As the thousands of climate activists come to town, a variety of warm weather records may fall in the D.C. area this weekend.

For example, if the overnight low temperature fails to fall below 70 degrees Fahrenheit on either weekend day, it would be the earliest such occurrence on record and a first for the month of April.

Washington has had its warmest April on record by far, with average temperatures so far coming in at more than 7 degrees Fahrenheit above average, according to the Post's Capital Weather Gang blog.

The record warmth itself is in line with recent temperature trends in many parts of the world, and in Washington.

"Over the past several years, Washington has set an astonishing number of heat records as greenhouse gas concentrations have soared to their highest levels in over 800,000 years because of human activity," wrote Jason Samenow, the Post's weather editor.

"Part of the warming trend in Washington is due to urbanization, but the accumulating greenhouse gases are stacking the deck for such extremely warm weather."

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