I think Thunder Gulch was a late May foal

Cannonade is one of 9 May foals that has won the derby since 1960 his foal  date 5/12/1971 is not the youngest.

Thunder Gulch is a late May Foal  5/23/92 , won the derby 5/6/1995  17 days before his 3 yr old foal date.

Not the Youngest foal date. Here is another  tidbit, His Sire line  and BMsire line have been 1st in a few Derby's.

Northern Dancer

Ah I know.  The Canadian.  

I like another Canadian this year.

Yes The Sire Of Sires, Held the Derby record Before Big Red, won the Derby NTR 2.00.00  foal date 5/27/1961

From His Dam's Natalma 1st crop when She was 4 years old when Northern Dancer was born

one of 15 first crop Dams that Threw A Derby Winner from 61 races. 27 mares have 1st or 2nd crop Derby winners from 61 races.

41 of 61 Derby winners Dams were within the first 4 crops of the Mare.

What Month  has the Least Derby Winners Foal Date Jan, Feb, March, April, or May since the 1960 Race?

I would guess January 

It would have to be between January and May.  You wouldn't want to mess up and have the foal come before Jan. 1st.  They'd have to race in South America lol.

That is correct 2 only January Foal winners since 1960, I think I started  this list around 2010 going back 50 years.

Grindstone 1/21/1993 foal date won in 1996, Proud Clarion 1/1/1964 first in 1967 , the 2 oldest 3's to win the Derby

in the last 61 years. its paid off 59 times to toss the January foals for the win in the last 61 runnings.

You Going To toss Epicenter for the win this year. 1/29/19. the only January foal in the top 20.

Why would you think the January foals are at a disadvantage?  Is the sample size large enough to conclude that there is a challenge with early foals?  I have the same question about #17 pp., or Amussen not winning, etc.