May 3: ORD

Today is May 3rd. It's the 124th day of the year. 242 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 66 and the normal low is 45. I've calculated the 33-year averages at 64 and 42.

On the warm side, in 2001 (O'Hare's second warmest May 3rd) the high was 86 with a low of 58. In 1999 the high was 78 with a low of 49. The other warm highs were 79 in 1982 and 78 in 1981. The other warm low was 57 in 1993. The record high of 92 was set in 1955 and the record warmest low of 68 occurred four years later in 1959. Both records were set at Midway. 15 of the last 33 highs (45%) were in the cool 50s. O'Hare's coldest high for the date was 49 in 1976. On the warm side, 18 highs (55%) were in the: 60s (7), 70s (10) and 80s (1). O'Hare's warmest May 3rd was in 1959 (high of 89 and low of 67). Both the high and low were O'Hare's warmest of the date. 

In looking back through the years to the first May at O'Hare in 1959, the following instances were notable: in 1978 the low was a cold 33 degrees. In 1976 the high was a cold 49 with a low of 37, a cold day. In 1973 the high was a cool 52 degrees. In 1972 the high was a cool 53 degrees. In 1971 the low was a cold 31 degrees. In 1970 the high was 73 with a low of 38, a 35 degree spread. In 1969 the high was a warm 82 with a low of 52, a 30 degree spread and warm day. In 1967 the high was 50 with a low of 31, a cold day. In 1965 the high was a warm 82 with a low of 48, a 34 degree spread. In 1964 the high was a warm 80 with a low of 49, a 31 degree spread. In 1962 the high was 77 with a low of 45, a 32 degree spread. In 1961 the low was a cold 32 degrees. In 1959 the high was 89 with a low of 67, a hot day.

More recently, we had a small spread of seven degrees in 1998 (56/49). The large spreads were 37 degrees in 1985 (71/34), 33 degrees in 1980 (76/43), 33 degrees in 1982 (79/46) and 30 degrees in 1981 (78/48).
 
On the cool side, in 2004 (O'Hare's second coldest May 3rd) the high was 54 with the record low of 30. The former record low of 32 occurred in 1971 at Midway. A year later, in 2005, the high was 52 with a low of 33. Last year, in 2011, the high was 50 with a low of 37. In 1983 the high was 51 with a low of 36. The other cool highs were 50 in 1987, 53 in 1984 and 53 in 2002. The record coldest high of 41 occurred back in 1935 at the University of Chicago. 29 of the last 33 lows (88%) were in the: 30s (13) and 40s (16). Four lows were in the warm 50s. O'Hare's coldest May 3rd was in 1967 as the high was 50 with a low of 31. 

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:15 and sunrise is at 5:46. Sunset is at 19:55 and twilight ends at 20:26. There's a total of 14 hours, 9 minutes of daylight today and 15 hours, 11 minutes between twilights. We gained two minutes of daylight from yesterday. Tomorrow twilight begins at 5:13 and sunrise is at 5:44. The moon is waxing gibbous and will be full in two nights at 22:35. Illumination was 88% at midnight, will be 91% at noon and 94% at midnight tonight. Moonset was at 3:52 this morning. Moonrise was at 17:17 this afternoon.  Moonset is at 4:26 tomorrow morning. Moonlight time is 10 hours, 35 minutes which is 44 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 ten days.