Well, here are the official records from US government source.

Yes, 120+ has been recorded a few times.

Still, Burning Man is more likely to be 82^o F that 100+, much less 120+.


State high temperature records

State          Temp    Date          Station                   Elevation (feet)
Ala.                112   Sept. 5, 1925   Centerville               345
Alaska          100   June 27, 1915   Ft. Yukon                420*
Ariz.               128   June 29, 1994   Lake Havasu               505
Ark.                120   Aug. 10, 1936   Ozark                     396
Calif.             134   July 10, 1913   Death Valley             N/A
Colo.             118   July 11, 1888   Bennett                   5,484
Conn.            106   July 15, 1995   Danbury                   450
Del.               110   July 21, 1930   Millsboro                20
Fla.                109   June 29, 1931   Monticello                207
Ga.                112   July 24, 1952   Louisville                132
Hawaii          100   April 27,1931   Pahala                   850
Idaho            118   July 28, 1934   Orofino                   1,027
Ill.                  117   July 14, 1954   E. St Louis               410
Ind.               116   July 14, 1936   Collegeville             672
Iowa             118   July 20, 1934   Keokuk                   614
Kansas       121   July 24, 1936   Alton                     1,651
Ky.                114   July 28, 1930   Greensburg                581
La.                114   Aug. 10, 1936   Plain Dealing             268
Maine            105   July 10, 1911   N. Bridgton               450
Md.                109   July 10, 1936   Cumberland and Frederick 623, 325
Mass.          107   Aug. 2, 1975   New Bedford and Chester   120, 640
Mich.             112   July 13, 1936   Mio                      963
Minn.             114   July 6, 1936   Moorhead                  904
Miss.             115   July 29, 1930   Holly Springs             600
Mo                118   July 14, 1954   Warsaw and Union          705, 560
Mont.             117   July 5, 1937   Medicine Lake             1,950
Neb.               118   July 24, 1936   Minden                   2,169
Nev.                125   June 29, 1994   Laughlin                  605
N.H.                106   July 4, 1911   Nashua                   125
N.J.                110   July 10, 1936   Runyon                   18
N.M.                122   June 27, 1994   Lakewood                  N/A
N.Y.                108   July 22, 1926   Troy                      35
N.C.                110   Aug. 21, 1983   Fayetteville             213
N.D.                121   July 6, 1936   Steele                   1,857
Ohio               113   July 21, 1934   Gallipolis                673
Okla.               120   June 27, 1994   Tipton                   1,350
Ore.                119   Aug. 10, 1898   Pendleton                1,074
Pa.                  111   July 10, 1936   Phoenixville             100
R.I.                  104   Aug. 2, 1975   Providence                51
S.C.                111   June 28, 1954   Camden                   170
S.D.                120   July 15, 2006   Kelly Ranch/Usta          2,339
Tenn.             113   Aug. 9, 1930   Perryville                377
Texas             120   Aug. 12, 1936   Seymour                   1,291
Utah               117   July 5, 1985   Saint George             2,880
Vt.                   105   July 4, 1911   Vernon                   310
Va.                   110   July 15, 1954   Balcony Falls             725
Wash.             118   Aug. 5, 1961   Ice Harbor Dam 475       475   
W. Va.             112   July 10, 1936   Martinsburg               435
Wis.                114   July 13, 1936   Wisconsin Dells          900
Wyo.                116   Aug. 8, 1983   Basin                     3,500

*Elevation estimated.

Source: U.S. National Climatic Data Center (last updated August 2006)