May 6: ORD

Today is May 6th. It's the 126th day of the year. 239 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.

According to the National Climatic Data Center (NCDC), the normal high is 67 and the normal low is 44. I've calculated the 32-year averages at 70 and 46.

On the warm side, in 2000 the high was 86 with a low of 62. In 1986 the high was 84 with a low of 63. In 2004 the high was 83 with a low of 55. In 1982 the high was 82 with a low of 54. In 1998 the high was 77 with a low of 58. In 2002 the high was 75 with a low of 60 (our most recent 60s low). Three years ago, in 2008, the high was 81. The other upper 70s highs were 78 in 1993, 77 in 1983 and 77 in 1988. The record high of 91 was set in 1949 and the record warmest low of 66 occurred in 1965. 14 of the last 32 highs (44%) were in the 70s. On the warmer side, five highs (16%) were in the 80s. 11 highs (34%) were in the cool: 50s (5) and 60s (6). Two highs (6%) were in the cold 40s (42 in 1989 and 48 in 1991). In the last five years (2006-10), all categories (except the 40s) have been represented. These are: 50s (58 in 2006), 60s (68 in 2007 & 63 in 2010), 70s (75 in 2009) and 80s (81 in 2008).

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: in 1976 the high was a cold 43 with a low of 35, a cold day. In 1975 the high was a cold 52 degrees. In 1974 the high was a cold 51 with a low of 36, a cold day. In 1970 the high was a cold 51 with a low of 34, a cold day. In 1969 the high was 78 with a warm low of 63, a warm day. In 1968 the high was 61 with a cold low of 31, a 30 degree spread. In 1967 the high was a cold 53 degrees. In 1966 the high was 70 with a low of 40, a 30 degree spread. In 1965 the high was 77 with a warm low of 66, a warm day. 1965 was the year of the record warmest low, also 66 at Midway. In 1964 the high was 77 with a warm low of just 65, a warm day. In 1963 the high was 69 with a low of 38, a 31 degree spread. In 1959 the high was a warm 85 with a low of 53, a 32 degree spread and warm day.

More recently, we had a small spread of six degrees in 1991 (48/42). The large spreads were 36 degrees in 1987 (76/40), 35 degrees three years ago, in 2008 (81/46), 33 degrees in 1993 (78/45), 33 degrees in 1995 (72/39), 32 degrees in 1980 (73/41), 32 degrees in 1988 (77/45) and 31 degrees in 1983 (77/46).

On the cold side, in 1989 we had our record coldest high of 42 with a near-record low of 31. The record low of 30 was set in 1992. In 1981 the high was 50 with a low of 36. Other cold or cool highs were: 48 in 1991, 53 in 1996 and 54 in 1994. 23 of the last 32 lows (72%) were in the: 40s (15) and 50s (8). Six lows were in the cold 30s. Our most recent 30s lows were: 37 in 1994, 39 in 1995 and 39 in 1996. Three lows were in the warmer 60s, most recently 60 in 2002. Of the most recent eight years (2003-10), five lows were in the 40s and three were in the 50s.

Where the most recent days stand over the past 33 years: Thu. 4/28: second coldest; Fri. 4/29: seventh coldest; Sat. 4/30: fourth warmest; Sun. 5/1: slightly above normal; Mon. 5/2: a bit below normal; Tue. 5/3: third coldest; Wed. 5/4: fifth coldest; Thu. 5/5: fourth coldest.

Today is a major day in Chicago's snow history. Twenty-two years ago (1989) we had half an inch of snow at O'Hare. Rockford had but a trace.

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight is 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 5:10 and sunrise is at 5:42. The moon is waxing crescent, having passed new three days ago at 1:51. Illumination was 8% at midnight, will be 12% at noon and 15% at midnight tonight. Moonrise is at 7:54 this morning. Moonset is at 23:28 tonight. Moonrise is at 8:53 tomorrow morning. Moonlight time is 15 hours, 34 minutes which is two minutes shorter than yesterday.

The warm part of Spring (Warm Spring) began on April 13. Warm Spring runs for 52 days, through June 3. High temperatures in this period are usually in the 50s, 60s and 70s. Warmer 80s and 90s occur infrequently. Mother's Day is in two days. -Bernie-