The best time to visit Temecula, particularly Temecula Valley Wine Country, is in spring and summer. This is when the vineyards are at their greenest, and the wines are at their best.  Fall is when the temperatures start to drop slightly, and the harvest season begins. You’ll find that the resorts and travel is cheapest in winter, but you won’t experience the vineyards at their greatest during this time. Still, this is an interesting time to visit Temecula’s wineries, as you might witness the fermentation process after the harvest season for a lot of wines.