According to Yahoo answers:

The greatest temperature change in 24 hours occurred in Loma, MT. on
January 15, 1972. The temperature rose exactly 103 degrees, from -54
degrees Fahrenheit to 49 degrees. This is the world record for a 24¡Xhour
temperature change.

Other Extreme Temperature Changes

In 24 hours:
100¢XF, Browing, MT, Jan 23¡V24, 1916, from 44¢XF to ¡V56¢XF.

In 12 hours:
84¢XF, Fairfield, MT, Dec 24, 1924, from 63¢XF at noon to ¡V21¢XF at midnight.

In 2 hours:
62¢XF, Rapid City, SD, Jan 12, 1911, from 49¢XF at 6 AM to ¡V13¢XF at 8 AM

In 27 minutes:
58¢XF, Spearfish, SD, Jan 22, 1943, from 54¢XF at 9 AM to ¡V4¢XF at 9:27 AM

In 15 minutes:
47¢XF, Rapid City, SD, Jan 10, 1911, from 55¢XF at 7 AM to 8¢XF at 7:15 AM

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