Global warming, check the data yourself, come to your own conclusions, not the ones you've been taught to believe (either for or against it). One source for quickly checking how the temperature for the US is doing recently is to compare it to the climatological temperature (the average temperature from the past 30 years). There's a really easy way to do that. Go to College of DuPage's weather data website and you find a ton of text weather data. Scroll towards the bottom and click on the state you wish to look at.
Once you get to the state page, you'll see that there is a huge list of things. What you are looking for are the climate reports. Pick any one and click it and it'll pop up. Climate reports tell you about the most recent day, but also tell you more information about the longterm. Down below Temperature, Precipiation, and such, they will have Degree Days. To calculate what the temperature has been doing, focus on the Departure From Normal column. Take the departure for cooling days, subtract the departure for heating days, then divide by how many days are in the period. For instance, I'm looking at a report that shows:

WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST       
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR       
                                                  NORMAL         
 HEATING
  YESTERDAY        6                         4      2        5         
  MONTH TO DATE   67                        42     25       17         
  SINCE SEP 1     67                        42     25       17         
  SINCE JUL 1     67                        43     24       17         
 COOLING                                                               
  YESTERDAY        0                         2     -2        0         
  MONTH TO DATE  104                       128    -24      194         
  SINCE SEP 1    104                       128    -24      194         
  SINCE JAN 1   1283                      1130    153     1552

To find out how this city is doing this month so far (today is the 29th of September), I'd do (-24 - 25)/29. I'd get -1.69... meaning they are 1.69F cool on average for the month. That's a pretty decent number over a month. If you get negative, they have been cool, positive they have been warm. Note that on this report, the longer periods (Jul 1 and Jan 1) don't match up, and so it's hard to get a year total. Some seasons the values reset for new conditions, and so they make it a little harder to track overall changes.
Your next job is to go around the country and get values for different locations. Try to get a good mix of cities from each part of the country, and different climate zones. The average should smooth out regional weather patterns because it is typical that while one area is hot, another is cool, based upon where fronts are and such. The overall average will give you an idea of whether there is an overall warm or cold streak going. It takes a little more work than a simple map... but it's also straight from the source. No one is editing these, the values come straight out of the daily readings. That's a big deal to me, because you can't always trust information that has been put together by people, as they'll selectively show you what they want to show you, or have peculiar ways to make it show what they want. These are raw numbers.