[ricks_place]

...where are the numbers coming from?...

Exactly! What is the source data after a site is decommissioned?

The US source sites were taken from surfacestations.org and the site status was found at NOAA Satellite and Information Service. The Maryland temperature data source sites are listed in the table below with the decommissioned sites crossed out. Seven stations stopped reporting in the 1990s!

COOP#	SITE	Post Office Dist Dir	STATE	LAT	LONG
180470	BALTIMORE WSO CITY	0.5 SE	MD	39.28	-76.62
181385	CAMBRIDGE WATER TRMT PLANT	0.4 W	MD	38.57	-76.07
181750	CHESTERTOWN	0.6 NE	MD	39.22	-76.07
181995	COLLEGE PARK	0.7 N	MD	38.98	-76.95
182282	CUMBERLAND	2 1.4 S	MD	39.63	-78.75
182523	DENTON 2E	1.6 E	MD	38.88	-75.8
183675	GLENN DALE BELL STN	1.5 SE	MD	38.97	-76.8
185111	LAUREL 3W	2.8 W	MD	39.1	-76.9
185985	MILLINGTON 1SE	1 SE	MD	39.27	-75.87
186620	OAKLAND 1SE	1 SE	MD	39.4	-79.4
186770	OWINGS FERRY LANDING	3.9 SW	MD	38.68	-76.67
186915	PATUXENT RIVER	0.5 N	MD	38.33	-76.42
187330	PRINCESS ANNE	1 NE	MD	38.22	-75.68
187806	ROYAL OAK 2SSW	2 SSW	MD	38.72	-76.18
188000	SALISBURY	0.6 E	MD	38.37	-75.58
189440	WESTMINSTER POLICE BRKS	3 SE	MD	39.55	-76.97
189750	WOODSTOCK	1 NE	MD	39.33	-76.87

[Free Vulcan]

I would pose the question at climateaudit.org and see what they say.

[Kevmo]

Bumpity bump, thanks for the information. Good digging.

[cogitator]

Thanks, I should have kept reading. For fun, stick the Baltimore coordinates into Google maps, zoom in, and then switch to the satellite view.

[4Liberty]

Good enough for gov work.