IMHO, there is no bad time for sangria. It's a perfectly appropriate brunch or dinner drink, and you can swap in different fruits depending on the time of year to make it taste ~seasonal.~ In the summer, I load up my sangria with peaches and strawberries whereas in the fall or winter I go with apple, pear, or cranberries. The one constant is basil. I always add a bit of basil to my sangria because fresh herbs balance the sweetness and make sangria totally next-level. To make sangria, I mix wine (red, white, or even sparkling), some fruit-flavored liqueur like Cointreau or St. Germain, and club soda. If you like your sangria on the sweeter side, add some simple syrup.
Recipe: Thai Basil Sangria