I know it's hard to think of during the hot months, but just go with it.
Mild Symptoms:
Shivering
Dizziness
Hunger
Nausea
Faster Breathing
Trouble speaking
Slight confusion
Lack of coordination
Fatigue
Increased heart rate
OR
D.I.L.H.N.T double F&S
Dizziness
Increased heart rate
Lack of coordination
Hunger
Nausea
Trouble speaking
Faster breathing and Fatigue
Slight confusion and Shivering
Dizziness
Hunger
Nausea
Faster Breathing
Trouble speaking
Slight confusion
Lack of coordination
Fatigue
Increased heart rate
OR
D.I.L.H.N.T double F&S
Dizziness
Increased heart rate
Lack of coordination
Hunger
Nausea
Trouble speaking
Faster breathing and Fatigue
Slight confusion and Shivering
Source: http://www.mayoclinic.org/diseases-conditions/hypothermia/basics/symptoms/con-20020453