Oh goodness - I had this - they were unbearable, and in August too. In the morning, it was like someone had poured a bucket of water on to my mattress. I went to GP because was also worried my c-section scar wasn't healing right (it was ok in the end). I think mine lasted about 8 weeks (sorry!) but GP didn't really have much advice as far as I remember, though he did take me seriously and said I was to check my temperature when they occurred - I never had a fever though. Here's some info from babycenter:
I've been sweating nonstop since giving birth. What's going on?
It's common to perspire a lot in the weeks after giving birth, particularly at night. Sweating is one of the ways your body rids itself of the extra water you retained during pregnancy.
Your kidneys are responsible for most of the purging, which means you'll be urinating more than usual for the first week after giving birth. But your pores also work overtime to shed the extra water. The emotional stress of new motherhood might be causing you to sweat more, too, and though no one knows for sure, it's possible that the dramatic drop in estrogen that occurs right after delivery also contributes.
Even after the water weight is gone, you may continue to sweat more than usual if you're nursing. Again, the cause is not well studied or understood, but theories include hormonal and metabolic changes associated with breastfeeding.
Although postpartum sweating is entirely normal, if it's accompanied by a fever, you could have an infection. Increased sweating can also be a sign of other problems, such as an overactive thyroid gland. Check with your healthcare provider if you have a fever or you think your sweating is excessive.
How long will it last?
Postpartum sweating can last several weeks after birth, though it tends to last longer for breastfeeding women.
What can I do about it?
Don't cut back on liquids in hopes of sweating less. Drinking lots of noncaffeinated, nonalcoholic fluids actually helps speed up the process of eliminating extra water and keeps you from getting dehydrated.