I have had 3 personal orders from various places in the us. All three of them have been late because of "late trailers".
There were no weather issues. I never see that from the USPS. I have notice that this happens quite often lately. Maybe you should change how many shipping days it will take.
Instead of listing 5 days maybe list 5-7, since it happens quite often. I would like to see the records of your shipping days across the us.
Next time I ship I will request using United States Postal Office instead of UPS. Please support them.