's birthday with fireworks displays , fire officials will be watching weather forecasts and preparing to make sure revelers are as safe as possible . They often start by banning spectators from a safety zone , or perimeter , around the launch site to protect them from drifting embers that can get as hot as 1,200 degrees Fahrenheit . For that reason , fireworks launches over harbors , rivers and other bodies of water can often be larger in scale . `` For a venue like New York Harbor , it is common for -LSB- launch -RSB- barges to be located on the water , well away from land , '' said Guy Colonna , division manager with the National Fire Protection Agency . `` Even if the winds increase , it 's possible ... -LSB- for -RSB- the safety of the display not to be compromised . '' Fireworks shows originating on land have stricter standards for the size of the perimeter , depending on wind speed , because spectators are generally closer to the explosives , Colonna said . Strong winds can make safety trickier . According to the Boston Globe , hundreds of people at a 2005
-LRB- CNN -RRB- -- In staging their Fourth of July fireworks show , authorities in Ocean City , Maryland , have faced challenges in recent years from Mother Nature . Fireworks light up the sky over Milwaukee , Wisconsin , during the city 's 2008 Fourth of July festivities . In 2005 , thick fog veiled the celebration . Spectators could n't see the detailed patterns and colors of the fiery blasts -- they only saw the clouds and haze get brighter . Thunderstorms erupted the next two years , delaying the show in 2006 and then forcing its cancellation in 2007 . That year , storms brought winds that were just too strong . `` We start taking a hard look at the direction and speed of the wind when it gets to 15 or more knots -LSB- about 17 mph -RSB- , '' said Ocean City Fire Marshal Sam Villani . `` At 20 knots , we consult the shooters ... to see if our perimeter is safe for the crowds . Twenty-knot -LSB- 23 mph -RSB- sustained winds would probably be our cutoff . '' As millions gather across the United States on Saturday to celebrate America