Hi there, I would use a higher factor suncream, or a sunblock, on your scars, or just make sure you keep them covered, at least for this year till they've had a chance to heal properly.
From reading around online it seems that scars are much more sensitive to sunlight than normal skin and at greater risk of burning - and once they are sunburnt they may remain dark, rather than fading, and will not return to the same colour as your healthy skin.
Hope that helps, enjoy our heatwave while it lasts!
Sharon x