From Wikipedia:
"Among the types of aircraft that have been used to investigate hurricanes, are an instrumented Lockheed U-2 flown in Hurricane Ginny during the 1963 Atlantic hurricane season. Other types include the A-20 Havoc, 1944; B-24, 1944–1945; B-17, 1945–1947; B-25, 1946–1947; B-29, 1946–1947. WB-29, 1951–1956; WB-50, 1956–1963; WB-47, 1963–1969; WC-121N 1954–1973; WC-130A, B, E, H, 1965–2012."
They were the WC121N, a military version.