You can consult the observations from Lancaster Airport as an alternative source of Lancaster data (although this site lacks quality control).

Monthly Summation of Surface Obs at MU

Daily Summaries for
May 2013

All values are calculated midnight to midnight unless otherwise noted. The times in
( )s are the times when the value occurred.
DateMax Temp.
(oF)		Min Temp.
(oF)		Dir. of
Peak Wind
(deg.)		Peak Wind
Speed
(mph)		Daily
Rainfall
(in.)
05/170
(14:52)		40
(05:54)		SE
(11:23)		17
(11:23)		0.00
05/272
(15:37)		39
(06:03)		SSE
(17:35)		15
(17:35)		0.00
05/368
(13:50)		44
(05:34)		E
(09:59)		18
(09:59)		0.00
05/471
(16:31)		38
(06:14)		SSE
(16:45)		16
(16:45)		0.00
05/566
(15:56)		39
(05:48)		SSE
(15:27)		15
(15:27)		0.00
05/665
(17:17)		40
(04:55)		ESE
(13:11)		14
(13:11)		0.00
05/771
(13:26)		53
(05:05)		SE
(17:15)		23
(17:15)		0.09
05/873
(14:56)		56
(22:51)		SSE
(17:32)		16
(17:32)		0.12
05/971
(16:36)		53
(06:05)		WSW
(13:52)		11
(13:52)		0.03
05/1080
(13:12)		51
(06:35)		NW
(20:09)		21
(20:09)		1.18
05/1172
(15:31)		61
(00:02)		WNW
(17:40)		14
(17:40)		0.26
05/1261
(00:00)		49
(22:37)		NW
(10:45)		23
(10:45)		0.01
05/1355
(16:12)		39
(03:49)		N
(16:06)		19
(16:06)		0.00
05/1461
(17:43)		33
(05:23)		NW
(14:30)		19
(14:30)		0.04
05/1573
(17:46)		49
(00:00)		S
(14:40)		20
(14:40)		0.05
05/1682
(15:39)		56
(04:30)		WNW
(17:22)		15
(17:22)		0.06
05/1777
(15:58)		58
(01:58)		NE
(13:40)		15
(13:40)		0.00
05/1869
(11:07)		57
(04:50)		SSE
(11:17)		18
(11:17)		0.03
05/1966
(16:00)		58
(00:00)		ESE
(06:44)		12
(06:44)		0.01
Total
Rainfall:		 1.88

Year-to-date rainfall: 12.78 in.
Max temp for the year: 88 (April 10)
Min temp for the year: 9 (January 27)