May 5: ORD

Today is May 5th. It's the 126th day of the year. 240 days remain. It's week 18 of the year.
 
Unless noted, the following data is based upon observations collected by the National Weather Service, Chicago, at O'Hare International Airport (ORD) between November 1978 and last year. ORD has been the official site of record for Chicago since Thursday, January 17, 1980. Before this, the official site of record was on the south side of Chicago at Midway International Airport (MDW), beginning on Wednesday, July 1, 1942. From Friday, January 1, 1926 through Tuesday, June 30, 1942, the official site was at the University of Chicago. Before that, the official site was at various locations in Chicago going back to Monday, October 16, 1871. Observations taken from October 15, 1870 to October 8, 1871 were lost in the Great Chicago Fire.

According to the National Climatic Data Center (NCDC), the normal high is 67 and the normal low is 45. I've calculated the 33-year averages at 69 and 46.

On the warm side, in 1982 (O'Hare's second warmest May 5th) the high was 88 with a low of 61. In 2000 (O'Hare's third warmest May 5th) the high was 84 with a low of 64. Two decades earlier, in 1980, the high was 88 with a low of 52, a 36 degree spread. In 1999 the high was 78 with a low of 61. In 1986 the high was 80 with a low of 58. The other warm low was 57 in 1985. The record high of 94 was set in 1949 and the record warmest low of 70 was set a decade later in 1959. Both records were set at Midway Airport. 25 of the past 33 highs (76%) were in the: 60s (15) and 70s (10). On the warm side, four highs (12%) were in the 80s. O'Hare's warmest May 5th was in 1959 (O'Hare's warmest high of the date of 92 with its warmest low of the date of 70). O'Hare's fourth warmest May 5th was in 1964 (high of 83, low of 64). Four highs (12%) were in the cold 40s.

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: in 1978 the high was a cold 43 with a low of 37, a six degree spread, year of the record coldest high and a cold day. In 1977 the high was 79 with a low of 59, a warm day. In 1976 the high was 78 with a low of 42, a 36 degree spread. In 1969 the high was 77 with a warm low of 60, a warm day. In 1968 the high was a cold 53 with a low of 34, a cold day. In 1967 the high was 52 with a low of 32, a cold day. In 1966 the high was a warm 83 with a low of 55, a warm day. In 1965 the high was 77 with a low of 47, a 30 degree spread. In 1964 the high was 83 with a low of 64, a warm day. In 1962 the high was 83 with a low of 60, a warm day. In 1960 the high was 77 with a warm low of 61, a warm day. In 1959 the high was 92 with a low of 70, a hot day. And although 1959 was NOT the year of the record high (94 in 1949), it was the year of the record warmest low (70 at Midway).

More recently, we had large spreads of 32 degrees in 1995 (72/40), 32 degrees in 2005 (70/38) and 30 degrees in 1988 (70/40).

On the cool side, in 1992 (O'Hare's second coldest May 5th) the high was 52 with the record low of 32. Three years earlier, in 1989, the high was 59 with a low of 37. The record coldest high of 43 occurred at Midway in 1978. 30 of the last 33 lows (91%) were in the: 30s (8), 40s (12) and 50s (10). Three lows were in the warm 60s. O'Hare's coldest May 5th was in 1978 (O'Hare's only 40s high of the date of 43 with a low of 37). Tied with 1992 as O'Hare's second coldest May 5th is 1967 (high of 52, low of 32). The lows of 32 in 1967 and 1992 were O'Hare's coldest temperatures of May 5th.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:12 and sunrise is at 5:43. Sunset is at 19:58 and twilight ends at 20:29. There's a total of 14 hours, 15 minutes of daylight today and 15 hours, 17 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:11 and sunrise is at 5:42. The moon is full tonight at 22:35 as the full Flower moon (a.k.a. Corn Planting or Milk moon). Illumination was 99% at midnight, will be 100% at noon and 100% at midnight tonight. Moonset was at 5:05 this morning. Moonrise is at 19:50 tonight. Moonset is at 5:51 tomorrow morning. Moonlight time is 9 hours, 15 minutes which is 38 minutes shorter than yesterday.  

Spring began on March 12th and runs for 84 days through June 3rd. Warm Spring began on April 13th and runs for 52 days through June 3rd. High temperatures in this period are usually in the 50s, 60s and 70s. Highs in the 80s and 90s occur infrequently. Mother's Day is in eight days. Armed Forces Day is in 14 days.