Wild temperatures continue

What a roller coaster ride!  On Monday, Sep 20, it was 99 degrees in BHM.  High temperatures stayed in the mid 90s all week, then the sudden change came over the weekend, when the first of two cold fronts droped temperatures a quick 15 degrees.  Another cold front last weekend dropped them another 10 or so, and suddenly we saw several nights last week with lows way down in the 40s.  BHM reached 39 degrees last Tuesday morning, coming within 1 degree of tying the record low (38, 1987).  Then, with the dry ground and high pressure, daytime temperatures went sky high again, and BHM tied a record high of 90 degrees yesterday. 

As far as departure from normal (I use the smoothed 114-year average) on daily temperatures, here’s how it breaks down, by day, for the past month.

Daily temperatures were 8-12 degrees above normal the week of 9/20, dropped slightly below normal the week of 9/27, and were as much as 14 degrees below normal last week (10/4).  Overall only 2 degrees above normal!  Talking about big temperature swings, how about that 99 on Sep 22, followed by a 39 on Oct 5?  That’s a 60-degree change in about 2 weeks.  I looked back at 30-day temperature ranges (lowest to highest) over the past 114 years. 

 The 60-degree range during the recent 30-day period is in the top 10 percent of these rapid temperature changes.  The biggest one occurred in 1899.   BHM’s coldest temperature ever recorded was on Feb 13, 1899 (-10 degrees).  But, by March 3, 1899, only 18 days later, it reached 81 degrees!  That’s a change of 91 degrees.  Wow.  Other notable temperature swings:

From 2 on 3/14/1993 (Blizzard of ’93) to 84 on 3/30, 82 degree swing.

From 70 on 11/23/1953 to 5 on 11/25 1953 (65 degree swing in 2 days)

From 68 on 12/3/1983 (Iron Bowl in severe storm) to 2 degres on Christmas morning, a 66 degree swing.

When will the roller coaster ride end?  Given Alabama weather, probably never.  But, the way-above normal heat from the weekend should go away by Wednesday, with a cold front dropping highs into the 70s.

Notable:  Our overall winter-to-summer change this past year was much larger than normal, also.  Compring average winter (Dec, Jan, Feb) lows to average summer (Jun, Jul, Aug) highs, this year had the second largest variation on record.  Our average winter low was 31.6 (top 10 coldest winters), and our average summer high was 93.4 (top 10 warmest summers), for a seasonal swing of 61.8 degrees.  The only larger change was in 1977, when the coldest overall winter on record was followed by a typically hot summer.  This is the first time we’ve had the top 10 coldest winter nights and the top 10 hottest summer days in the same year.

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