DNA samples stored at room temperature for long periods of time can degrade and lose genetic material. However, a study found that DNA extracted from buccal cells that were stored at room temperature for three days did not show a significant difference in PCR amplification products compared to samples collected immediately.

https://doi.org/10.7171%2Fjbt.13-2404-001

Definitely but the advice is to have an ice pack

That would rely on a variety of parameters in your DNA storage tube, including buffer quality, DNA purity after extraction (is there RNA, protein, or even DNases contamination), contamination during storage, etc.