Considering that Dante Alighieri’s almost always depicted with a red cap, it’s hard to imagine what his actual hair colour’s like. Boccaccio described his hair as dark but Alighieri himself described it as akin to yellow*, especially when he wrote it in Italy.
Here’s an excerpt from the book, Dante: The Poet, The Think and The Man:
Nonne triumphales melius pexare capillos
Et patrio redeam si quando abscondere canos
Fronde sub inserta solitum flavescere Sarno?
More glorious, were it not, to groom my hair,
Now become white which formerly was fair,
Concealed in leaves entwined in Arno’s shore,
When to my homeland I return once more.
Algihieri certainly grew grey with age but like I said in my previous posts, he might not be as blond as others make it out to be but not as dark as Boccaccio remarked. He could be fair-haired in comparison to his peers, moreso in his youth though one would suggest that his surname is of Germanic origin and Germans are stereotyped as blond. Whether or not he had blond hair is speculative, he could even have brown hair just not that dark.
*Flavus is the Latin word for yellow and blond, which allegedly gave way to the latter word.