Of all the visitors to Churchill Downs on May 2 for the Kentucky Derby Presented by Woodford Reserve, the one who could have the biggest impact on the day is Mother Nature.

Rain and a wet track can be a godsend to some starters and a curse to others, and these days it is becoming harder to compile evidence on who are the mudders in the field of 20.

In California, horses cannot train on a wet track and heavy rain can lead to a cancellation of the card. Most trainers will also shift workouts so their horses can drill on a fast surface.

As a result, of the prospective field of 20, only one of the 17 American probable starters have wet track experience. The foreign candidates have better resumes in that regard with two of three having raced on a wet track.

Wood Memorial Stakes runner-up Right to Party (Coady Media)

Of the U.S.-based runners, only Right to Party has experience on a wet track. He closed for third on a good surface in the Gotham Stakes at Aqueduct, 7 ½ lengths behind Iron Honor. The son of Constitution earned his spot in the Derby field by grabbing second in the Wood Memorial Stakes Presented by Resorts World Casino next time out.

Golden Tempo could be one to watch on a wet track. He has the breeding to handle it as a son of Curlin and on Nov. 21 at Keeneland he posted a bullet work of :47 2/5 on a good surface.

Commandment, Potente, and Renegade, as sons of Into Mischief, would also seem to have the breeding to run to expectations on a wet track.

As for the foreign runners, Danon Bourbon is 2-for-2 on wet tracks in Japan. The son of Maxfield won the Fukuryu Stakes by 3 ½ lengths and a maiden race by 10 lengths, both on muddy surfaces.

United Arab Emirates Derby Sponsored by Jumeirah winner Wonder Dean was second by a half-length in the Mochinoki Stakes and broke his maiden by eight lengths in a maiden race. Both races were on tracks rated good in Japan.

Another useful tool for predicting whether or not horses will thrive on an “off” track is the Tomlinson rating, especially since the majority of Kentucky Derby entrants have no experience on a wet track. Daily Racing Form uses Tomlinson ratings to make an educated guess how racehorses will handle wet tracks based on performance of the horse’s sire and broodmare sire’s progeny on wet tracks. For the Kentucky Derby field, the table below lists the contenders from high (best for a wet track) to low:

Note: AE - denotes also-eligible, which means the entrant would need at least one defection or more to secure a spot in the starting gate. * indicates a small sample size of data.

The progeny of many of the top sires in North America — Into Mischief, Gun Runner, and Curlin are good examples — perform very well on off tracks, so the number of entrants for big races with strong Tomlinson ratings for wet tracks is typically high. Twelve of the 20 entrants in the main body of the Kentucky Derby field have a Tomlinson rating above 400 with Emerging Market, Further Ado, Fulleffort, morning-line favorite Renegade, and Golden Tempo all above 425. Twinspires.com Louisiana Derby winner Emerging Market and Toyota Blue Grass Stakes winner Further Ado, in particular, could get a boost if the mostly cloudy forecast for May 2 at Churchill leads to rain on Derby day.

Last year marked the fourth time since 2017 that the opening leg of the Triple Crown was contested on a wet track. It didn’t seem to affect the outcome as the 1-2-3 finish of Sovereignty, Journalism, and Baeza held up on a dry track in the Belmont Stakes.

Sovereignty and Journalism are sons of Into Mischief and Curlin, respectively.

As for this year, we’ll see what Mother Nature has to say everything.