It seems to me that the original question is a little ambiguous. First, most people equate the following names for shoe colors: cordovan, burgundy, merlot (Allen-Edmonds), wine, oxblood. Thus, to many shoe fans asking whether cordovan (the color) is suitable--ignoring burgundy--doesn't make sense. One could ask whether that color range of dark-reddish browns is suitable for summer wear (in my opinion, it is), but to say that cordovan is not, whereas burgundy is, will make shoegeeks shake their heads. The truth of the matter is that one shoe maker's or shoe polish's "cordovan" will be redder than another's "burgundy," whereas the phenomenon will be reversed with two other brands of shoes or polish. Second, the usual question is whether cordovan--meaning the material shell cordovan leather--is suitable for summer. In answer to that question, many people in hotter locations consider it unsuitable because it is so dense and impermeable, that one's feet will sweat in it on hot summer days. In more temperate climes, however, I doubt that shoes of that material would cause problems, even in mid-summer.