Some surface station temperature data links:
1. USHCN (United States Historical Climate Network) monthly
data through 1994 (obsolete, see item 3, but included for
is the main online documentation file.
2. USHCN daily data through 2002 (daily max/min, you get to
calulate means, monthly, etc.)
is the main online documentation file.
3. USHCN monthly data through 2002
is the main online documentation file, and
provides an overview.
USHCN includes a station history file with summaries of station
changes, including location, time of day of observation, etc.
GHCN (see below) does not include such "metadata", which is quite
unfortunate. The USHCN monthly files include various sets with
successive adjustments, some of which are briefly discussed in
The stations in the three USHCN groupings have varied slightly;
check the respective "inventory" files.
The above USHCN collections include data from stations within
the contiguous 48 US states only. For data from stations
around the globe, including USHCN stations, see below.
4. GHCN (Global Historical Climate Network)
Monthly data including their most recent data available
(excluding some recent data for some stations for which they
include older data, such as the South Pole (Amundsen Scott, which
is available at:
stations from Iceland, (available at:
and who knows what else).
Temperature files in pkzip compressed form are at:
and in unix, or gzip, compressed form are at:
is the main documentation file, with a bit more in a readme file.
Don't fall off your chair when you read:
"The reason why GHCN mean temperature data have duplicates while
mean maximum and minimum temperature data do not is because there
are over 100 different ways in which daily mean temperature has
been calculated by meteorologists."
A brief summary on GHCN "quality control" is at:
The GHCN has a country codes file, but not a station history
file, whereas the USHCN has station history files, with more
detailed "metadata", and more extensive documentation overall.
They both have station "inventory" files, which list the id codes
for each station, as well as such things as lattitude and
longitude. In GHCN terminology, there are stations,
locations, sources, and duplicates. It appears to me that
duplicate refers to multiple sources for one location, or station,
but might also refer to multiple stations in, or near, one location.
In this text I use the word station as a synonyn for location,
but there is much ambiguity among these terms.
For many stations the GHCN has no recent data; their old data is
included simply to preserve it in a convenient place for
5. GISS has GHCN monthly mean temp data conveniently available
(i.e. by station, rather than all/many stations in one big file) at:
watch out for their adjustments. GISS no longer includes USHCN
"raw" data, just adjusted data, and GISS does not include any
Update 18 Jan 2005: It now appears that GISS excludes temperature
data for years prior to 1880 from the files available at that link.
Annual means at GISS are Dec-Nov, while the USHCN uses Jan-Dec.
The GHCN lets you roll your own. The USHCN uses Fahrenheit, GISS
uses Celsius, and GHCN omits the decimal point, so its files are
in tenths of degrees Celsius. All of these temperature data
files are ASCII fixed format files. GISS files, and the USHCN
daily files, are blank delimited; the others are not. GISS
files each refer to one "station" or "location"; the others
include many stations in each file.
About station changes: over periods of many decades, there will
usually occur various kinds of station changes, for examples:
kind of thermometer, location of thermometer, time of day of
reading, or observation, and/or station operator. In the history
files that accompany the USHCN collections, there are summaries
of such changes (metadata). If you examine, for example, the
USHCN mean monthly temperature file of the most recent USHCN
collection (item 3 above) you can notice that virtually every
station change results in a change to adjustments to the
temperatures for that station. While one may question the
accuracy of those adjustments, at least there are data on which
to base most of them. On the other hand, the GHCN collection
does not include such metadata, and the GHCN adjusted
temperatures cannot be expected to be as accurate as USHCN
adjusted temperatures, however accurate the latter may, or may
Happy data dunking! Caution: it may become habit forming.
18 January, 2005