Spring is the most rewarding time to visit Lleida. From late February through April the orchards of the Segre plain burst into blossom — apricot, peach, cherry, and apple — and the countryside around the city becomes genuinely beautiful. The light is good, temperatures are mild, and the Pyrenees to the north are still snowcapped.
May brings L'Aplec del Caragol, the world's largest snail festival, held on the last weekend of the month on the banks of the Segre. Hundreds of thousands of people descend on Lleida to eat snails cooked every possible way, drink local wine, and dance. It is chaotic and wonderful; accommodation books out months in advance.
Summer is hot and dry — the plain bakes under a relentless sun, though the old city stays reasonably cool in the mornings and evenings. Autumn is pleasant, with the harvest in and the hills beginning to colour. Winter is cold and sometimes foggy in the valley, though clear days offer the best views of the Pyrenees from the cloisters of La Seu Vella.
Avoid visiting on Mondays, when many museums and monuments are closed.