Ask when to come and most people say May or September, the two months with mild weather, thinner crowds and average temperatures between 45 and 60 °F. Each season still has its own case, so here is how the year actually feels.
Autumn
Autumn turns the parks gold and brown, and temperatures drop to around 40–50 °F, or 5–13 °C, from late September. The Royal Botanic Garden is the spot for the foliage, with good color on Calton Hill and along the Water of Leith as well.
Winter
Winter is cold and the days are short, with highs that rarely get past 45 °F, or 7 °C, and fog and wind sweeping in off the Firth of Forth. What you get back is the festive version of the city: the Christmas Market in Princes Street Gardens, an ice rink on George Street, and Hogmanay fireworks over the castle.
When the cold keeps you inside, the decorations give you a reason to go back out. Both the Old and New Towns are dressed for the season, so a short walk after dark is a plan of its own.
Spring
Spring is bright and warming, with highs from 30 to 50 °F, or 3 to 13 °C. The Meadows and Princes Street Gardens come back to life, and the cherry blossoms turn pink against the castle. It is the best window for Arthur's Seat before the summer crowds arrive, or for a walk along the Water of Leith Walkway through Dean Village and Stockbridge.
Two events land in spring: the Edinburgh International Science Festival in April, and the Beltane Fire Festival on Calton Hill on April 30.
Summer
Summer stays cool here, and that is the point. Even August, the hottest month, averages just 66 °F, or 19 °C, so eating outside in the Grassmarket or in Leith is a real option instead of a gamble.
August is the peak, when the Fringe and the Military Tattoo on the Castle Esplanade fill every venue in the city. For the quieter days, the Royal Yacht Britannia in Leith, a day trip into the Scottish Highlands, and Portobello Beach all work on a warm afternoon.