In the face of the largest human displacement ever recorded in modern history more than 79.5 million persons around the world have been forced to flee their homes worldwide at the end of 2019, from which 30 million are refugees. However, most shelters lack actual capacity to provide adequate thermal control for much of the year time; whereas many are located in regions with hard weather conditions, most fail to maintain temperature and humidity within accepted human comfort levels. This fact triggers ad hoc users' responses that compromise their sense of security, privacy, and belonging, and in some cases, challenge their cultural traditions. This study evaluates the thermal performance of the three most common UNHCR's shelters design for refugees assigned to the three extreme climatic regions facing this crisis worldwide: Jordan, Afghanistan, and South Sudan and links with the regional particularities. Seasonal analyses are carried out through computer simulations contrasted with data collected in-situ. The study also tests variations of the thermal performance of each shelter type under the other climate locations seeking for potential matches. Findings show that UNHCR's shelter type A has the best regulation of humidity levels and potential for exportation, and that type C has the best performance for thermal stability although greater difficulties and application for rapid deployment. The study concludes with a detailed assessment of current designs' strengths and weaknesses that could inform future shelter designs or alterations of existing units to improve refugees' living conditions.