Modern awning fabric has water- repellent properties. But persistent humidity is still potentially damaging for your fabric. If it is retracted, the woven fabric cannot dry. Discolouration is formed due to water stains. Furthermore, moisture favours fungal infestation. This will lead to mildew.
Therefore: Always ensure that your awning is dry!
Note: Never extend the awning when it is raining.
Otherwise water puddles could be formed, which would damage both fabric and awning. If the awning becomes wet, simply retract it wet and extend it again and leave it to dry at the next opportunity.