What to wear to Holi in Mathura: Mathura sits at 31°C (88°F) by day and 16°C (61°F) at night in March, on city streets, with a low chance of rain. That means loose natural fabrics and real sun protection, cushioned trainers or a low boot, and a bag small enough for the gate rules. The crowd leans water, party and costume, so a full costume is the norm rather than the exception.
Men's festival dressing at Holi in Mathura comes down to three decisions: how much you can take off when it hits 31°C (88°F), what you put back on at 16°C (61°F), and whether your shoes can take city streets for 2 days.
The short version: White cotton you are happy to ruin, sunglasses against the powder, and oil in your hair so the colour washes out.
The dominant aesthetics at Holi in Mathura are get-soaked practical, party, full costume and parade. That is the visual language of the site, the stages, the merch, the crowd photos, and outfits that speak it look intentional rather than borrowed.
This is a costume festival, and that changes the maths: turning up in normal clothes is the conspicuous choice. Budget for one full look rather than three half-hearted ones, and make sure you can walk, dance and queue in it for eight hours.
What people actually wear: as little fabric as the venue allows, in natural fibres, with a bag small enough to forget about; something identifiable, a colour, a hat, a flag, so your group can find you in a crowd of that size.