Trump vows to deliver delayed US 250th birthday speech in Washington despite storms, heatwave evacuations and mounting political tensions.

Trump vowed to deliver a "really long" Fourth of July address despite a 107-degree forecast at the America 250 celebration.

The president's speech capped an Independence Day eve otherwise most notable for a brutal heat wave that gripped much of the eastern part of the country.

By Belinda Robinson in Washington DC |

America's 250th birthday was marked by celebrations across the nation, though a severe heatwave and approaching thunderstorms disrupted events in Washington D.C. President Trump's…