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FILE - In this Saturday, May 7, 2011 file photo, John Velazquez rides Animal Kingdom to victory during the 137th Kentucky Derby horse race at Churchill Downs in Louisville, Ky. Although Louisville is best known for the Derby, visitors in town for the May 5, 2012 race will find plenty of other things to do and see around town, from museums to historic hotels to trendy restaurants-AP. (AP Photo/Michael Conroy)

The weather for the 138th annual Kentucky Derby will be summery, but that includes the risk of a thunderstorm.

The weather over the Ohio Valley through Saturday will teeter on the edge of 90-degree air and sunshine to the south and a zone of clouds, thunderstorms and near 80-degree temperatures to the north.

The zone of showers and thunderstorms will meander back and forth across the Ohio Valley through this week. What the weather is like for the derby and earlier events will depend on which way the zone decides to shift.

Some drenching downpours will pass over the track this week. Portions of Missouri, within the zone of storms, have received between 2 and 4 inches of rain during the 24-hour period ending at 9:00 a.m. CDT, Monday. Portions of Kansas and Oklahoma have been with between 8 and 12 inches of rain spanning Sunday and Monday.

Storms swept through the Louisville area Monday evening with a quick half-inch of rain.

Statistically, according to the National Weather Service in Louisville, Ky., it has rained on 46 percent of derby days. Thunderstorms have been in the vicinity of Louisville during six of the last 20 derby days.

The wettest derby day was May 11, 1918, when 2.31 inches of rain fell on Louisville.

This year's Kentucky Derby has the potential to be the hottest since May 2, 1959, when the temperature hit 94 degrees.

Depending on the amount of sunshine, temperatures could reach near 90 degrees. During the derbies held in 2000 and 2001, temperatures hit a high for the day of 86 degrees.

The details of the weather and the prospects for thunderstorms during the 138th Annual Kentucky Derby will unfold as the week progresses.

While thunderstorms have been a risk in the past for the derby, concerns for safety during various outdoor sporting events have been raised recently.

Thunderstorm winds vary tremendously over distance. In a downburst, winds can exceed 100 mph in a relatively small area. During a downburst, downdrafts hit the ground and spread out in all directions or can be concentrated in one direction.

In early May of 2009, a thunderstorm downburst struck the Dallas Cowboys training tent, causing it to collapse. Dozens of people were injured.

Five people were killed and 40 were injured at a Sugarland concert held the Indiana State Fair Grounds in August of 2011. Downburst winds from a thunderstorm caused the stage to collapse.

A thunderstorm hit the vicinity of Busch Stadium in St. Louis, Mo., this past weekend. Strong winds during the storm blew over an outdoor tent, which injured dozens of people. Some reports suggest that a man who was killed in the incident died as a result of a lightning strike.

As a reminder to coaches, camp supervisors and facilities managers, any thunderstorm has the potential to bring a concentrated area of high winds and there is no way to accurately predict where lightning will strike.

Generally, if you can hear thunder, there is the risk of a lightning strike in your vicinity.

The only real safe place to be during a thunderstorm is in an enclosed building, away from windows. If that is not available, a hard-top vehicle with its metal frame can offer adequate protection.

According to the National Oceanic and Atmospheric Administration (NOAA), the odds of you being struck by lightning in your lifetime is 1 in 10,000. During the period from 2001 to 2010, an average of 280 people were hit by lightning annually.

Tents, pavilions, golf carts and open areas in a stadium are not safe places to be. While the metal superstructure of a stadium will discharge the electrical current to the ground, there is still the risk of a direct strike on people in the stands.

This story was first published on Monday, April 30, 2012 and has been updated.