The Far-East is very sensitive in its awareness of food "temperatures". Not the physical temperature of food, but the heating or cooling effect different foods have on our systems. I'm tempted to believe we were aware of this at least once upon a time in the West, with terms like "cool as a cucumber" still surviving and referring to spicy food as "hot". I don't know about anyone else, but I still break into a sweat when I eat spicy food, even after seven years in Korea.
Caffeine is generally hot, though somehow green tea is the only tea that is cool. Puerh tea is known for its ability to keep you warm, and oolong teas range in between. From this, its easy to figure about which teas are best at what times of year.
In early spring, my favourite tea is oolong, especially delicate high-mountain oolong from Taiwan, and in the evening, I'll rotate through my collection of darker traditional Chinese oolongs, such as Phoenix Oolong, our Da Hong Pao. When spring starts heating up, I find myself craving green tea, especially in the morning. This is also the time of year that green tea is harvested, which is nice, because green tea is best at its freshest. I try to use up all of my green tea by summer's end, before they begin to deteriorate. Also, by this time, Chinese oolongs from that spring, have begun to develop their flavours. When the crisp airs of autumn arrive, my craving for green tea disappears, and I start digging out my puerh cakes, which were mostly left untouched during the long, muggy summer months. Puerh is an excellent winter tea, especially if you're going to spend much time outside. At night, a nice aged puerh not only warms you up, but also has a mellow personality. The micro-organism in the tea also help keep you immune system strong through the harsh weather.
There isn't a time of year that I don't drink lots of oolong. Like green tea, high-mountain oolongs and Tie Kwan Yin (Iron Buddha/Iron Goddess of Mercy) tend to loose their fragrance quickly, so I drink them more often in the spring and summer. Traditional Chinese oolong and Taiwan's famous Oriental Beauty, or White Hair tea, depending on what farm it's from, taste better after at least six months. Fittingly, high-mountain oolong and Tie Kwan Yin are also some of the most lightly fermented teas and though they give me the most energy, I don't notice much lasting heat from them.
The only tea I don't drink with any regularity are English black teas. The plants that are cultivated in India and Sri Lanka are slightly different from Chinese ones. They have a higher level of caffeine and I find myself unsteady and with a bit of a headache after drinking them. If you do like them, these teas have quite a lot of heat and are also very good during chilly weather. In China, there are similar types of tea, known as red tea, but I've yet to try them.
A newer development in Korean tea is Balhyo Cha, fermented green tea, also called Hwang Cha, yellow tea. The first time I tried it, I had a similar feeling as black tea, but one day, I found myself craving to try it again and have become a big fan of it. It also has a fair amount of heat and I'll probably be drink a lot of it as the chilly nights creep further across the days.