June and July saw relentless heat centred from Denver to St Louis with days on end in the 90s or 100s. It was a pattern straight out of the 1950s, 1988 and of course the 1930s with the return to a cold PDO and onset of the El Nino. These factors greatly aid in supporting a dry pattern over the Plains and when dry, it’s more often than not, hot too.
This July was declared the hottest July and month in United States history, even hotter than the infamous July of 1936. I, like others have a hard time seeing how that was the case when you compare the two months in the below charts. Though the NET TEMPERATURE of the Lower 48 may have been higher in July 2012 compared with July 1936, the local and state records which fell over a broader area was far much impressive back in 36′.
Here was July 2012
Here was July 1936
Even July 1934 looked more impressive
I guess my point with this is that only 1 state saw it’s warmest July on record last month and that was Virginia while back in 36′, there was 8 states which saw their hottest on record. Last month saw no below normal and yes in 36′ there was 6 states well below normal with Maine seeing their coldest on record. Texas obviously covers a vast area of the nation and it was well below normal but those 8 states which saw their hottest July and month on record was much hotter than anything experienced last month. It’s tougher to get 8 states with outstandingly hotter than normal temperatures with all-time record highs in both cities and the state falling than to have a broader area with warmer than normal. I hope that makes sense. With the exception of July 2006 where Usta, South Dakota tied the South Dakota all-time record high set in 36′ with 120°, there is no state across the Northern Plains or even central Plains for that matter which have gotten anywhere near those levels seen back in July 36′ when we saw temperatures hit 120 in every Plains state except Nebraska but they too hit their hottest on record at 118°. The thermometer read an astonishing 121° as far north as North Dakota and 114° in Minnesota and the stunning all-time record shattering heat spread all the way to New York where Central Park reached 106°, a benchmark which still stands today. The heat last month, as relentlessly hot as it was, didn’t see all-time records for even a single month never mind all-time over the Plains and Midwest which makes last month less impressive in my opinion despite the bigger area of the country seeing warmer than normal conditions.
Of course I am not forgetting the incredible heat seen from Nashville, TN to Atlanta to Norfolk, VA. That was outstanding but again, explainable given the pattern.
If it’s the hottest ever, why aren’t we seeing more all-time records falling, especially with the help of urbanisation?
It is easier for heat records to fall these days than back in the 1930s thanks to much larger areas covered by heat retaining asphalt and concrete. I personally believe it’s the urban heat island which is to blame for Las Vegas, Phoenix, Tucson Denver and Salt Lake City and the Coachella Valley of California which are staying hotter for longer through the night and likely the reason why America’s fastest growing city (Las Vegas) tied their all-time record of 117° back in July 2005. The important aspect is that despite Vegas being 2, 3, 4 times larger than back in 1900 and perhaps twice the size than when it last hit 117°, the thermometer wasn’t able to surpass the 117° back during the July 2005 heatwave. Nowhere else in the Southwest broke any significant record except daily records over the past 10 years which has seen tremendous expansion and growth. The hottest, fast growing Phoenix has reached in the last 10 years is 118° back last July, the hottest ever recorded remains unbeaten.
My point is, it had to be hotter in these areas as well as out and across the Plains before than now because if it’s hotter now and when factoring in the heavy urbanisation of particularly the West, records would have been obliterated in the past 10 years. Upper ridges aren’t any stronger than before. Night lows are setting records more easily and this is a direct result of urbanisation and not because days are hotter.
Many stunning heat records date back BEFORE the industrial revolution. The period from the 1920s through 50s when the majority of heat records were set. Co2 levels are far higher now than then yet if this is the cause oif warming, why aren’t we seeing all-time records fall all over? Yes, we do see all-time records but not the the extend you would expect to see if the Co2 argument was really true. We cannot beat these records today which were set back some 80 years ago.
In summary, I put this down to NATURAL warm and cold spells on earth and nothing else.
Back to the point in this post!
While the heat has been relentless from Denver on east throughout June and July and one could argue, since March, the West Coast has been cool but now that we’ve hit August, the heat is easing from the Plains and Midwest with cooler Canadian air working down. The core of the heat has now shifted into the very areas which have had a fairly subpar summer of 2012.
Los Angeles & San Diego are now running are finally running above normal following a colder than normal May, June, July. Last 7 days have been hottest all summer from LA to Vegas
You know it’s been a cool summer in Southern California when June and July averages 1-2° below normal and the maximum for June is 82° and July is 92° in Downtown Los Angeles. Yesterday saw a tie for summer’s warmest day yet with 92°. Not a big deal really. June averaged -1.2° while July saw a full 2° below normal.
In often cool, naturally air conditioned San Diego, May, June and July were all stuck with the AC stuck on perminantly with both June and July averaging exactly 1.3° below normal. June was no better with the month alsoi ending 1.3° below normal with daytime monthly maximums of only 81° and 76° respectively.
Even out in the ‘gaurenteed HOT’ inland deserts and despite a scorching 119° high on July 10, Palm Springs averaged 0.5° below normal last month with most days only warming into the low 100s. There was also 5 days which failed to hit 100° with the final day of the month only reaching 88°, chilly given the average high is 108°.
In contrast, this month so far is averaging nearly 5° above normal with every day topping 100° and 5 out of the past 6 days topping 110°.
8 of the last 10 days has topped 120° in Death Valley
For the hottest of hot and the very worst of summer heat, most in the US and North America turn to Death Valley. Like, Palm Springs, despite a very impressive high of 128 set back on July 11 and the world record breaking low of 107, a daytime high just 3 afternoons following, only warmed to 100, an amazing 17° below normal.
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