Despite a modest June that featured temperatures just ever-so-slightly above average (0.2 degrees to be exact), our hot start in 2012 continues to translate to a pace for warmest year on record. The first half of 2012 is averaging 54.72 degrees, 0.84 degrees ahead of the pace set in 1991 and over a degree ahead of the pace set in 1998.
An "average" year based on the 1981-2010 time frame would feature a January-June temperature of 50.53 degrees. This year is running 4.19 degrees above that average. 2010 ranks 6th warmest through June.
Of the years listed on the sample, the warmest for all twelve months (1931) is not listed in the top 8 through June. 1998 ended up 2nd warmest at year's end, 1991 ended up 3rd. 2010 ended up 5th and 2011, which wasn't ranked through June, ended up 4th...boosted by a very warm late Fall and December.
Our "warmest first half of the year" on record isn't just an honor that we can hang our hats on, it was for the nation as a collective whole and a host of other climate sites throughout the US. In terms of a charted comparison year-to-date, you can see 2012 compared to 1991 and 1998 below, with this year the bold red line.
If we average 'average' for the duration of the year, we will end up with the 4th warmest year on record. If we end up a half a degree above average from here on out, we will score a record setting warm year in Philadelphia. Given our current pace, it's pretty likely we'll see one of the warmest years on record...whether it's the warmest or not is still a bit early to say but our recent heat wave definitely will aid in pushing us towards an annual record.