May 7: ORD

Today is May 7th. It's the 128th day of the year. 238 days remain. It's week 19 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 46. I've calculated the 33-year averages at 67 and 46.

On the warm side, in 2000 the high was 77 with a low of 64 (O'Hare's warmest low of the date). In 1979 the high was 81 with a low of 57. The other warm highs were 84 in 1988 and 83 in 2007. The record high of 87 was set in 1964 at Midway. The record warmest low of 68 occurred way back in 1880, at a time when the official readings were taken adjacent to Lake Michigan. 30 of the past 33 highs (91%) were in the: 50s (10), 60s (9) and 70s (11). On the warm side, three highs were in the 80s. O'Hare's warmest May 7th was in 1964 as the high was 85 (O'Hare's warmest of the date) with a low of 61. O'Hare's second warmest May 7th occurred the next year (1965) as the high was 83 with a low of 61.

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 cool 53 and in 1977 the high was a cool 54. In 1976 the high was 52 with a low of 33, a cold day. In 1974 the high was 54 with a low of 32, a cold day. In 1973 the high was 60 with a low of 53, a seven degree spread. In 1972 the high was a cold 47 with a low of 42, a five degree spread and cold day. In 1970 the high was 78 with a low of 38, a 40 degree spread. In 1969 the low was a warm 58 degrees. In 1966 the high was 73 with a low of 35, a 38 degree spread. In 1965 the high was 83 with a low of 61, a warm day. In 1964 the high was 85 with a low of 61, the year of the record high (87 at Midway) and a warm day. In 1963 the high was a warm 81 with a low of 49, a 32 degree spread. In 1960 the high was a cool 51 with a low of 36, a cold day.

More recently, we had small spreads of four degrees in 1998 (59/55) and five degrees in 1999 (58/53). The large spreads were 44 degrees in 1988 (84/40), 37 degrees in 1992 (71/34), 36 degrees in 2007 (83/47), 35 degrees in 1985 (73/38) and 34 degrees in 2006 (71/37).
 
On the cool side, in 1989 the high was 57 with the record low of 29. In 1981 the high was 59 with a low of 32. The other cold low was 34 in 1992. The other cool highs were 53 in 1994 and 55 in 2004. The record coldest high of 43 occurred back in 1931 at the University of Chicago. 25 of the last 33 lows (76%) were in the: 40s (16) and 50s (9). Seven lows (21%) were in the cold: 20s (1) and 30s (6). One low (3%) was in the warm 60s. O'Hare's coldest May 7th was in 1976 (high of 52, low of 33). O'Hare's coldest (and only 40s) high of 47 occurred in 1972.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:09 and sunrise is at 5:41. Sunset is at 20:00 and twilight ends at 20:31. There's a total of 14 hours, 19 minutes of daylight today and 15 hours, 22 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:08 and sunrise is at 5:39. The moon is waning gibbous, having passed full two nights ago at 22:35 as the full Flower moon (a.k.a. Corn Planting or Milk moon). Illumination was 98% at midnight, will be 96% at noon and 93% at midnight tonight. Moonset was at 6:45 this morning. Moonrise is at 22:13 tonight. Moonset is at 7:46 tomorrow morning. Moonlight time is 8 hours, 32 minutes which is 14 minutes shorter than yesterday. Moonlight time is at its least today and tomorrow.  

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 six days. Armed Forces Day is in 12 days.