Barra is most enjoyable from May to early September, when the days are long, the wildflowers bloom on the machair, and most boats and tours are running. June is the driest month; July and August bring more visitors and slightly warmer (relative) temperatures.
Winter is dark and stormy, with ferries regularly cancelled by Atlantic gales — beautiful but only for hardier travellers. The Barrathon, a half-marathon around the island in mid-July, draws a small crowd of runners and is a good excuse for a visit if you like to combine sport with travel.