Predicting the weather on race day is about as easy as predicting lottery numbers. Is it going to be cloudy or cloudless, rain or shine, snow or sleet? As of now, the weather for Saturday, June 25 according to weather.com the weather should be almost perfect for a race, High's in the upper 60's and lows in the lower 50's with partly cloudy skies and winds at 5 mph from the southwest. One thing to consider anytime you go out for a run, regarding temperature, add about 10 to 15 degrees to the actual temperature. This will help offset the build-up of body heat during your run. You should start the race/run cool, not warm. If you often find yourself ending your runs holding loads of clothes it's because you started with too much on.
Hats - Hats are great for keeping rain out of your face and sun off the top of your head. Brightly colored hats will even act as good eye-catchers to drivers, further increasing the likelihood you'll be seen and cars will move over to a comfortable passing distance. Hats on race day can also be a great way for your friends and family to help identify you through the crowds.
Tops - Often bright, and hosting logos. Shirts and jackets act as your main identity around other runners. The materials should be made of synthetic blend fabrics (usually, nylon and polyester). Jackets are great for cold to cooler weather running and come in a variety of different weights. The warm the temperature the lighter the jacket. Jackets can also act as rain guards, but be careful because they'll also hold in heat some be sure to chose rain jackets at cooler temps. Shirts will come in a variety of types: long sleeve, short sleeve, no sleeve, and tanks. Wear what you're comfortable in, the hotter and calmer the wind the less you need, however, on sunny days be sure to wear shirts that have UV protection to help protect against harmful sun rays.
Gloves - Gloves should be worn when the temps dip low enough, usually under 50 degrees. If it's going to be cold and wet make sure the glove has some type of weather blocking material on the top of the hand.
Bottoms - Shorts, Long Pants, Tights, Capris, and Skirts. Lots of variation in this category. The length of the short/skirt doesn't have any correlation to race day/run success. If you like 'em short wear 'em short, if you'r a bit more conservative wear 'em long. Long pants, tights, and capri pants are great for temps below 45 degrees and windy days.
Socks - The key to comfortable feet is to wear properly fitting shoes and comfortable socks. Cotton socks may be comfortable during the work day, when you're running cotton tends to saturate rather quickly and hold in the moisture and heat which can cause the fabric to bunch leading to hot spot blisters. Wearing socks that are synthetic or wool will help reduce moisture saturation and heat build-up.