April 18: ORD

Today is April 18th. It's the 108th day of the year. 257 days remain. It's week 16 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 59 and the normal low is 38. I've calculated the 32-year averages at 63 and 40.

On the warm side, in 2002 the high was the record high of 89 with a low of 63. The former record high of 88 occurred at Midway in 1977. In 1985 the high was 83 with a low of 62. In 2004 the high was 86 with a low of 52, a 34 degree spread. A decade earlier, in 1994, the high was 84 with a low of 50, a 34 degree spread. In 2005 the high was 83 with a low of 45, a 38 degree spread. In 1996 the high was 76 with a low of 51. A year earlier, in 1995, the high was 76 with a low of 47. In 1987 the high was 77 with a low of 45, a 32 degree spread. Other warm highs were 75 three years ago (in 2008) and 73 two years ago (in 2009). The record warmest low of 66 was set way back in 1896. 22 of the last 32 highs (69%) were in the: 50s (9), 60s (7) and 70s (6). On the warmer side, five highs (16%) were in the 70s. On the cold side, five highs (15%) were in the: 30s (1) and 40s (4).

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1977 the high was 86 with a low of 59, a warm day. This was also the year of the former record high (88 at Midway). In 1976 the high was 80 with a low of 57, a warm day. 1972 the high was a warm 77 with a low of 45, a 32 degree spread and warm day. In 1969 the high was a cold 46 with a low of 40, a six degree spread. In 1967 the high was a cold 46. In 1966 the high was 76 with a low of 50, a warm day.

More recently, we had a small spreads of seven degrees in 1999 (45/38) and seven degrees in 2003 (46/39). There were large spreads of 37 degrees 1986 (69/32), 33 degrees two years ago (in 2009) (73/40), 32 degrees in 1980 (70/38) and 30 degrees three years ago (in 2008) (75/45).

On the cold side, in 1983 the high was 37 with the record-tying low of 23. The low of 23 first occurred way back in 1875. Six years later, in 1989, the high was 45 with a low of 34. Other cold lows were 26 in 1997 and again in 2001. Other cold highs were 45 in 1999, 46 in 2003 and 47 in 1984. The record coldest high of 35 was set back in 1926. 23 of the last 32 lows (72%) were in the: 30s (15) and 40s (8). Four lows (12%) were in the cold 20s. Five lows (16%) were in the warmer: 50s (3) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:39 and sunrise is at 6:08. Sunset is at 19:38 and twilight ends at 20:07. There's a total of 13 hours, 30 minutes of daylight today and 14 hours, 28 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:37 and sunrise is at 6:07. The moon is was full last night as the full Pink (a.k.a. Sprouting Grass, Egg or Fish) moon at 21:44. "Pink" moon refers to the wild ground phlox. The moon is now waning gibbous. Illumination was 100% at midnight, will be 99% at noon and 98% at midnight tonight. Moonset is at 6:03 this morning. Moonrise is at 20:54 this afternoon. Moonset is at 6:45 tomorrow morning. Moonlight time is 9 hours, 9 minutes which is 42 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) began five days ago. 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. Good Friday and Earth Day are in five days. -Bernie-