Behind the Forecast: The Kentucky Derby vs. Kentucky weather

Listen to Science Behind the Forecast with Meteorologist Tawana Andrew every Friday on 89.3 WFPL at 7:45 a.m.
Updated: Apr. 30, 2021 at 9:20 AM EDT
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Legendary photographer Dan Dry is sharing his Derby Week images with WAVE 3 News again this year.
Legendary photographer Dan Dry is sharing his Derby Week images with WAVE 3 News again this year.(Dan Dry/PriceWeber)

LOUISVILLE, KY (WAVE) - All eyes are on Churchill Downs for the Kentucky Derby.

Weather can play a big role in horse races, especially when it comes to the track.

There are three types of horse racing tracks: dirt, turf, and synthetic. The weather can quickly change turf and dirt track conditions. Synthetic tracks are more consistent regardless of the weather, according to

Dirt tracks are some of the most popular tracks in the United States. Churchill Downs boasts a one-mile oval track that’s made of “12-inch resilient clay base on top of a 25-foot sandy loam sub-base”, according to their website. Eight inches of a sifted and mixed combination of 75% round river sand, 23% silt, and 2% clay sits on top of the clay. Churchill Downs’s website explains that the top three inches act as the cushion for the horse while the five inches below “protects the horse from ever reaching the sturdy base.”

Crews must take care of dirt tracks in all weather conditions. They harrow, roll, seal, grade, and sometimes water the track depending on the weather. A chain harrow is pulled behind a tractor, breaking up the dirt and helping to create a more even surface. Then the track is watered depending on the existing moisture content and sealed and smoothed with a float. A float is a sheet of metal or wood with weights that is dragged over a race track to help with water drainage and smoothing and compacting the surface of a race track.

The various conditions for dirt tracks in North America are as follows:

  • Fast: Dry.
  • Wet-Fast: The track has a wet surface, but moisture has not been able to penetrate the lower layers of the track.
  • Good: A surface that is drying out or has had recent, but not much rainfall.
  • Muddy: A wet surface, that tends to have slower times than a good surface. Moisture has seeped towards the track base.
  • Sloppy: A very wet track with water visible on the surface. The base is still quite solid The rain might still be coming down or stopped; drying has not yet begun.

According to Mick Peterson of the Racing Surfaces Testing Laboratory, who has worked with Churchill Downs, stated in an interview with Science that the cushion layer of horse racing tracks works best when it is 14% water. Watering the track can help to offset evaporation while sealing can help to keep water out. Even the shadows of a race track’s grandstand can impact a track, causing some areas to dry out faster or stay wetter longer than others.

Legendary photographer Dan Dry is sharing his Derby Week images with WAVE 3 News again this year.
Legendary photographer Dan Dry is sharing his Derby Week images with WAVE 3 News again this year.(Dan Dry/PriceWeber)

One advantage of turf is that dirt and mud aren’t thrown into horses’ and jockeys’ faces during racing. Turf can still be significantly impacted by the weather. Overuse can dry out a turf course. Race tracks often use breaks in racing to seed and fertilize their turf tracks.

Churchill Downs has a ⅞ mile oval with a sand base. On top of that, the turf is made up of 90% fescue and 10% Kentucky bluegrass. Churchill Downs site states that the inside rail is rotated regularly between lane 1 (on the hedge), lane 2 (15 feet off the hedge), and lane 3 (22 feet off the hedge). The course also has a “state-of-the-art drainage system under the turf to ensure that the course dries quickly.”

The conditions for turf tracks in North America are as follows:

  • Firm: There is little moisture and the surface is resilient
  • Good: A turf course with some moisture, and softer a firm course.
  • Soft: A course with a lot of moisture than a good course, and significant give.
  • Yielding: A very wet turf course with ample “give”.
  • Heavy: The wettest possible turf course; basically waterlogged

In November 2020, Churchill Downs announced that they would be inventing $10 million to install a new turf course. The plan is to widen the running surface while increasing the turf’s durability to allow for more turf racing throughout the year. Work on the project is expected to start after the 2021 Spring Meet. It is expected to be ready for the 2022 Spring Meet; it could be ready by November 2021 if growing conditions are good. The new turf course is expected to be made of fescue and bluegrass with a redesigned subsurface. The turf track is expected to be expanded from 80 to 85 feet; it could accommodate up to 14 horses per race.

(WAVE 3 News)

A GoingStick, or penetrometer, is used by tracks around the world to measure a course’s conditions. It sinks into the soil in several locations to determine the soil’s hardness and an average is taken to determine the rating.

Synthetic tracks aren’t as popular now as they were in the early 2000s. While the exact mixture for the various types of synthetic tracks does differ, most of made of fibers, sand, and rubber covered in wax. Two of the most popular types are Polytrack and Tapeta. Keeneland installed Polytrack in the fall of 2004 and actually worked to help market it in the United States, the New York Times explained. However, Polytrack was removed from Keeneland in 2014.

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