Answer first: for a lyophilised solid, transit temperature matters far less than people assume, and transit duration matters mainly because of what it does to the cold pack rather than to the peptide.
Reported ranges from Chinese origins to western Europe cluster around nine to fourteen days with tracking, with inland origins adding a domestic leg and coastal ones sometimes beating the range.
Anything shipped in solution is a genuinely different risk, because hydrolysis and deamidation proceed in the aqueous phase and are strongly temperature-dependent.
Nothing here is medical advice, and research-use compounds are not approved for human use.
Lyophilised solids tolerate ambient transit. That is the whole answer for most orders.
edited 8 Mar 2025 by g_paskevicius — reworded for clarity after a comment