Arthropod-borne diseases negatively affect humans worldwide. Understanding the biology of the arthropod vectors and the pathogens they harbor, the arthropods are moving targets as a result of climate change, ecosystem degradation, species introductions, and increased human travel. Viruses within the California serogroup of the genus Orthobunyavirus (family Bunyaviridae) are among the mosquito-borne viruses of concern owing to their zoonotic potential. Two of these, snowshoe hare virus (SSHV) and Jamestown Canyon virus, were shown, using a combination of serology and virus isolations, to circulate on the Island of Newfoundland, Canada, in the 1980s. More recently, serological analysis demonstrated that these two viruses continue to circulate on the Island in several domesticated and wild animals. Here, we detected the seroconversion to SSHV in wild snowshoe hares and in a single sentinel rabbit. The seroconversion in the sentinel rabbit occurred in early August (2011), which corresponded to the weeks of peak mosquito collections and the timing of the detection of SSHV in suspected mosquito vectors. A portion of the SSHV S segment sequence was generated from mosquito pools collected at sites near the sentinel rabbits and phylogenetically analyzed using the neighbor-joining method with other available California serogroup virus sequences. This analysis validated the SSHV identification but showed that the Newfoundland sequence fell outside the other SSHV sequences available, which originated from the United States between 1959 and 2005.