ASHRAE Technical Committee 4.2 regularly (every 4 years) updates the design conditions data in the ASHRAE Fundamentals (latest version 2009).

Chapter 14 Climatic Design Information contains all the normal cooling and heating design conditions (1, 2, 99, 99.6) but a lot more. And the WDView program allows users to look at frequencies, joint frequency matrices, custom bin the data, and calculated degree-days to any base.

A new version of the Fundamentals (2013) is due out this spring with updated period of record (1986-2010) and a new version of the WDView program (5.0).

The design conditions ARE showing the changes in climate due to urbanization and climatic trends.

The soon-to-be-published Chapter 14 says:

" Differences from Previously Published Design Conditions

? Climatic design conditions in this chapter are generally similar to those in previous editions, because similar if not identical analysis procedures were used. There are some differences, however, owing to a more recent period of record (generally 1986-2010 versus 1982-2006). For example, when compared to the 2009 edition, 99.6% heating dry-bulb temperatures have increased by 0.31?F (0.17?C) on average, and 0.4% cooling dry-bulb temperatures have increased by 0.18?F (0.10?C) on average. Similar trends are observed for other design temperatures. The root mean square differences are 0.74?F (0.41?C) for the 99.6% heating dry-bulb values and 0.70?F (0.39?C) for 0.4% cooling dry-bulb. The increases noted here are generally consistent with the discussion in the section on Impacts of Climate Change.

? Further details concerning differences between design conditions in the 2009 edition and 2005 edition are described in Thevenard (2009). Differences between the 2005 edition and the 2001 edition are described in Thevenard et al. (2005). Differences between the 1993 and previous editions are described in Colliver et al. (2000)."

And

"Effects of Climate Change

...

For 1274 observing sites worldwide with suitably complete data from 1977 to 2006, selected design conditions were compared between the period 1977-1986 and 1997-2006. The results, averaged over all locations, are as follows:

? The 99.6% annual dry-bulb temperature increased 2.74?F (1.52?C)

? The 0.4% annual dry-bulb increased 1.42?F (0.79?C)

? Annual dew point increased by 0.99?F (0.55?C)"

As Joe Huang and others have noted, NREL recently updated the NSRDB to contain data through 2010. The NSRDB (US locations only) was the source for the TMY3 and a project to create TMY4 is planned. Environment Canada is also updating the CWEC (Canadian locations) to more recent period of record and more locations as well. The recently released ASHRAE IWEC2 provide another 3,012 locations outside of the US and Canada.

As others have noted, there are also AMYs (actual meteorological years) with records up until the last few months available from different sources now including gridded data to 1 kM.

It's a lot better than where we were before 2005 with TMY2 (only 239 US locations) and CWEC (originally 55 and now 80 locations)!