Remember our seasonal Yoga? Here I wrote about spring Yoga https://goo.gl/a45ggd.
Every season that comes bring with it new energy, and we can adjust our Yoga practice accordingly.

Summer is time of light and warmth, so when we practice Yoga we want to achieve energy of cool and calm.
Hot temperature outside also means we lose our temper, get impatient. This season is represented in Ayurveda by fire and water.
Excess heat can present itself as rushes, burns (sunburn incl), anger and irritability.
  
Usually Yin Yoga is recommended in the summer, a type of flow that is slower, remaining in each pose for longer time. Yin Yoga also helps us connect more inward to our body and mind. Staying in a pose for between 2-3 minutes can be soothing and contemplative.  
It gives us time to surrender to the present moment, to be still, to breath.

Start with Pranayama called Sheetali (in Sanskrit it means cooling).
Send your tongue out and fold the sides of it (like you create a straw). If genetically you cannot do it, make an o (very small) opening with your mouth instead.

Breath in, take the cool air inside through the rolled tongue, count for 4-5, then close your mouth. And breath out through your nostrils. Exhale for 5-6 count. But do not force it. Repeat 5 or six times.

This cooling pranayama is lowering the body temperature, reduces the “fight and flight” stress and calm you down. It has positive effect on the endocrine and nervous systems, it removes excess heat accumulated in the system.

Another Pranayama recommended is Sheetkari. With mouth open, clench your teeth (jaws) together and put your tongue between them. Breath in.
Close your mouth and breath out from the nostrils. Repeat5-10times.

This Pranayma also helps to quench thirst and it is cooling the body.

Postures you can practice are:

Low lunge with opening the chest. Child’s pose, Hero pose, Sphinx pose, Forward bend, Butterfly pose, lion pose, bridge pose, legs on the wall, fish pose, floor twist, savasana (corpse pose).