An urban heat island (UHI) is a metropolitan area which is significantly warmer than its surroundings. As population centres grow in size from village to town to city, they tend to have a corresponding increase in average temperature, which is more often welcome in winter months than in summertime. The EPA says: "On hot summer days, urban air can be 2-10°F [2-6°C] hotter than the surrounding countryside. Not to be confused with global warming, scientists call this phenomenon the 'urban heat island effect'"
Its quite simple to actually see the effects of this mystical UHI effect...When our weather is good to us, and its been a scorcher of a few days, if you are lucky enough to own and drive either a convertable car, or a motorcycle, then go for a ride in the dead of night in the town and out to open country side, then come back....The heat change hits you in the face in no more than half a mile apart from the two different areas...Towns and built up areas are just like storage heaters at night, yet less than half a mile into open land its so much cooler... As an ex resident of town living for more than 30 years, and an ex night worker working in a place surrounded by fields that was only a couple of miles from my ex home, belive me i know the difference in temperatures....So then, when does these experts take readings on temperatures, or where.....Sounds a bit like used car salesmans talk to me, you know what i mean, its a lovely car sir, only had 1 owner who only used it to go to church on sunday (that church was 5,000 miles away i recon..lol..)