There’s nothing like beautiful San Diego weather. Any time of the year is great for visiting and enjoying the perfect climate. Temperatures peak around 80 degrees Fahrenheit during summer days, cooling off to about 65 at night. Winter highs tend to be around 70 during the day with lows near 50 at night. The city typically gets over 300 days of sunshine per year, making it a great spot for a beach vacation. Bring cool clothes, sunglasses and a light jacket, and you’ll be all set to relax and soak up the sun.
Because of the perfect weather, the summer months are the most popular time for tourists to visit, and the beaches, hotels and roads can become crowded during the tourist peak. If you want to avoid the crowds while still enjoying the warm weather, come in the early spring or late fall. Visiting in the late fall, the weather is still summery enough to visit the beaches!
During May and June you may experience the phenomena of "May gray" and "June gloom". Typically this occurs when the coastal clouds hang in low along the coast and the sun doesn't shine through. It can remain gray all day but often by noon the clouds will lift. During those times you can often drive a few miles inland away from the ocean to find the sun.
Remember the winter months are the rainy months here. And if you're from the east coast, always bring a light sweater (summer) and/or jacket (thicker in the winter time) because it's not humid here and the ocean breeze keeps things relatively cool, especially at night.