Wind Resistance levels that you will see associated to Drones are maximum levels of wind gusts that the device can operate in.
The scale is from 0 to 12. Where a Wind Resistance level of 0 is typical ‘no wind’ (or gusts of less than 1 mile an hour.) and 12 is approximately 74 mph.
Most drones (with the exception of kids toys and indoor drones) should have a Wind Resistance Level of 5 – 7 this would be in the range of 20 – 38mph
So it is essential that you check typical weather in the areas you will be flying.
The 0-12 scale is essentially the Beaufort Scale but always check the notes / ratings from your chosen drone supplier.