Lolita is a difficult fashion when it comes to surviving your country's climate. In winter it can be too cold to wear, in summer too hot. Here a few tips.
Wear lighter colors. White reflects more sunlight than black, thus keeps you cooler. Also try to wear items that are made of cotton and have as little lining as possible. It makes the dress thicker and because it's often made of synthetic fabric, it makes you sweat more. If you're afraid of sweat stains (like me), avoid white blouses. In my opinion, the Jewel Neck Lace Cotton Sweet Lolita Dress is your best choice, which is from ocrun.com. Its sleeveless pleated design and jewel neckline with venice flower-shaped lace accented on its trim make this kind of sweet lolita very beautiful and lovely .
It is made of cotton. You will feel very cool and sexy with this dress at summer.
Bloomers aren't always sufficient. Wear tights underneath them, made of special thermal fabric are even better. Cover your legs with boots, and wear short socks underneath your tights so that your toes don't freeze. Wear a shirt (made of thermal fabric) underneath your blouse or OP and a cardigan. Use lots of layers.