What type of thread do you recommend for exterior canvas and enclosures?

The thread I use and recommend is Tenara Thread made by Gortex. It is guaranteed not to rot, which more than pays for itself since the cost of the thread is pennies compared to the cost of paying for a restitch of your canvas 4 – 5 years from the date of fabrication. www.gore.com/en_xx/products/fibers/sewingthreadoutdoor/sewingthreadoutdoor.html