( CNN ) -- 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 [ about 17 mph ] , '' 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 [ 23 mph ] sustained winds would probably be our cutoff . '' As millions gather across the United States on Saturday to celebrate America '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 [ launch ] 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 ... [ for ] 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 Fourth of July fireworks show in Canton , Massachusetts were accidentally showered with glowing embers when winds shifted about 10 minutes after the event began . High winds can even cancel a fireworks celebration . Rain , however , will not necessarily stop a show , said Philip Butler of Fireworks by Grucci , a Long Island , New York-based fireworks production company that has choreographed shows for presidential inaugurations and the Olympics . Fireworks do n't extinguish in the rain , and as long as operators `` keep the powder dry , '' they will explode , Butler said . Moisture can cause them to change colors , though . `` A brilliant blue may appear as a royal blue , '' he said . Weather challenges are nothing new for Grucci . In preparing for a large show in Dubai , the production company once faced 105-degree heat and a sandstorm . `` They told us to simply kneel down and cover our heads with our capes and ride it out , '' Butler said . Ideal conditions for fireworks are calm winds , comfortable temperatures and clear night skies , Butler said . `` When the sky is black and clear , it 's like a painter 's canvas for us . '' Some commonly asked questions about fireworks : . Do fireworks still work when it snows ? Yes . For many New Year 's Eve celebrations in cold-weather states , it 's often snowing during fireworks shows . Fireworks production companies say the snow acts as a prism , reflecting and shifting the colors . What 's the biggest danger that spectators face from fireworks ? Statistics show the vast majority of fireworks-related injuries are caused by over-the-counter fireworks instead of burning debris from public fireworks celebrations . The risk of fireworks injury is 2½ times higher for children than for the general population , according to the National Fire Protection Agency . The biggest culprit ? Sparklers . The National Fire Protection Agency advises against using your own fireworks . `` Leave it to the professionals . '' For a Fourth of July weather forecast for your area , visit CNN.com/weather .
High winds and rainstorms can pose serious challenges to fireworks shows . Severe weather affected fireworks three of past four years in Ocean City , Maryland . Winds can cancel a fireworks celebration , although light rain often will not . One fireworks company weathered a sandstorm before a show in Dubai .