WETM-TV (channel 18) is a television station in Elmira, New York, United States, affiliated with NBC and owned by Nexstar Media Group. Its second subchannel serves as an owned-and-operated station of The CW (via The CW Plus), as Nexstar owns a majority stake in the network. WETM-TV's studios are located on East Water Street in downtown Elmira, and its transmitter is located on Hawley Hill in Big Flats, New York.

The first user of channel 18 in Elmira was its second station, WECT, which was operated by El-Cor Television, a joint venture of the Corning Leader and the Elmira Star-Gazette. The station only operated for less than a year, from September 30, 1953, to May 27, 1954. El-Cor surrendered the station's license in September.

In late 1955, plans surfaced from two groups to reactivate channel 18 for use as a rebroadcaster of another station, one from Triangle Publications, owner of WNBF-TV of Binghamton, and one from the Newhouse group, owner of WSYR-TV of Syracuse. After WNBF-TV dropped its proposal at the end of November, WSYR-TV was granted the construction permit by the FCC on April 4, 1956, and broadcasting began on September 15 under the callsign WSYE-TV. The station telecast from the same Hawley Hill site used by WECT; like its parent, it was an NBC affiliate. While most programming came from Syracuse, the station did originate some programming from the Hawley Hill site.

In 1980, Newhouse sold its entire television division, including WSYR and WSYE, to the Times Mirror Company. The new owners changed the call letters to WSTM-TV and WETM-TV, respectively. Times Mirror gradually cut the last ties between the two stations while establishing WETM-TV as a full-fledged station in its own right. It sold WETM to Smith Broadcasting in 1986. Smith moved the station's studios and sales units to a more central facility in Elmira in 1988. Under Smith's ownership, a reversal of the station's origins took place with the April 1996 launch of a cable-only Binghamton version of WETM-TV (known as "NBC 5") through a local marketing agreement with Time Warner Cable, which would displace WNYW from cable systems in that area. Set up in the wake of WICZ-TV, Binghamton's established NBC affiliate, defecting to Fox, the arrangement saw Time Warner Cable sell Binghamton-market advertising and replace syndicated programs that aired on other Binghamton stations with programming acquired by WETM-TV for the Binghamton market due to syndex laws, while WETM-TV sold regional advertising seen in both markets. In 1997, Smith bought Binghamton low-power station WBGH-LP and made it an over-the-air semi-satellite of WETM-TV; WBGH eventually split off except for simulcasting WETM-TV's newscasts. WETM-TV became the first outlet in the Elmira market with an internet presence starting in 1998.

In 2000, Smith Broadcasting entered into a management agreement with The Ackerley Group to operate WETM-TV. Clear Channel Communications inherited the management agreement when it purchased Ackerley in late 2001. In 2004, Smith Broadcasting sold WETM-TV outright to Clear Channel after the death of Smith Broadcasting founder Robert Smith. On April 20, 2007, Clear Channel entered into an agreement to sell its entire television stations group to Providence Equity Partners. Newport announced on July 19, 2012, that it would sell twelve of its television stations (including WETM-TV) to Nexstar Broadcasting Group. The sale was finalized on December 3, 2012. On July 26, the station was knocked off the air by widespread power outages caused by a confirmed tornado that struck downtown Elmira during the afternoon. By the next day around mid-morning, WETM-TV had a feed restored to Time Warner Cable.

WETM's second subchannel has its roots in W30AA, a translator of PBS member station WSKG-TV in Binghamton. That station closed down the translator in 2003 after concluding the expenses required to operate W30AA were not justified by its limited viewership base. WSKG subsequently sold the W30AA license to Clear Channel, which brought it back on-the-air in September 2004 as UPN affiliate WTTX-LP (identified on-air as "UPN 30"). At this point, it began to be seen through a simulcast on WETM-TV's second digital subchannel, since its analog broadcasting radius was very limited. It replaced WPIX of New York City on local cable systems.

With the September 2006 merger of UPN and The WB to form The CW, WTTX competed to become the area's affiliate. Ultimately, this went to cable-only WB 100+ station "WBE", which was operated by rival ABC affiliate WENY-TV. WTTX was dealt another blow when WSKG launched full-time satellite WSKA on the channel 30 allotment, forcing Clear Channel to shut down the low-power station; it never moved to another channel, and instead its programming became a subchannel of WETM-TV, known as "WETM2". It aired coverage of local high school sports, Elmira Jackals hockey, and New York Yankees baseball. The channel started airing Antenna TV programming in 2020.

The subchannel became an owned-and-operated station of The CW Plus at 6 a.m. on September 1, 2025. Antenna TV was shifted to 18.3, replacing Laff.