April 15: ORD

Today is April 15th. It's the 105th day of the year. 260 days remain. It's week 15 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 58 and the normal low is 37. I've calculated the 32-year averages at 60 and 40.

On the warm side, in 2002 the high was the record high of 88 with a low of 62. A year later, in 2003, the high was the record-challenging high of 86 with a low of 64. Last year, in 2010, the high was 82 with a low of 61. In 2004 the high was 75 with a low of 46. The former record high of 84 occurred at Midway in 1976. Other warm highs were 73 in 1982 and 72 in 2000. Another warm low was 49 in 2006. The record warmest low of 67 occurred at Midway in 1976. 20 of the last 32 highs (62%) were in the: 50s (11) and 60s (9). On the warmer side, six highs (19%) were in the: 70s (3) and 80s (3). On the cold side, six highs (19%) were in the 40s.

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 79 with a low of 49, a 30 degree spread and warm day. In 1976 the high was 82 with a low of 65, a warm day and year of the record warmest low. In 1973 the high was a warm 75 with a low of 44, a 31 degree spread and warm day. In 1971 the high was a warm 71 with a low of 35, a 36 degree spread. In 1969 the high was 61 with a warm low of 55, a six degree spread. In 1967 the high was 73 with a low of 54, a warm day. In 1964 the high was 62 with a low of 30, a 32 degree spread. In 1963 the high was a warm 73 with a low of 32, a 41 degree spread. In 1962 the high was a cold 42 with a low of 28, a cold day. In 1960 the high was 72 with a low of 49, a warm day. In 1959 the high was a warm 71 with a low of 41, a 30 degree spread.

More recently, we had small spreads of five degrees in 1984 (42/37) and six degrees in 1993 (47/41). There were large spreads of 35 degrees in 1997 (66/31), 32 degrees in 1982 (73/41), 32 degrees in 2000 (72/40) and 30 degrees in 2005 (63/33).

On the cold side, in 1983 the high was 40 with a low of 29. Three years later, in 1986, the high was 40 with a low of 31. Other cold highs were 42 in 1984, 45 in 1980 and 45 in 1996 (our most recent 40s high). The record low of 25 was set back in 1943 and the record coldest high of 34 occurred back in 1928. 27 of the last 32 lows (84%) were in the: 30s (15) and 40s (12). Two lows were in the cold 20s and three lows were in the warmer 60s. There have been no lows in the 50s.

Today is a major day in Chicago's snow history. 1961 was the year. O'Hare had 1.2 inches, the first of two days of 5.9 inches of snow. Midway had 1.1 inches, the first of three days of 6.8 inches of snow. Rockford didn't record any snow today, but stay tuned tomorrow!

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:44 and sunrise is at 6:13. Sunset is at 19:35 and twilight ends at 20:04. There's a total of 13 hours, 22 minutes of daylight today and 14 hours, 20 minutes between twilights. We gained four minutes of daylight from yesterday. Tomorrow twilight begins at 5:42 and sunrise is at 6:11. The moon is waxing gibbous and will be full in two days as the full Pink (a.k.a. Sprouting Grass, Egg or Fish) moon at 21:44. Illumination was 88% at midnight, will be 92% at noon and 95% at midnight tonight. Moonset is at 4:25 this morning. Moonrise is at 16:59 this afternoon. Moonset is at 4:55 tomorrow morning. Moonlight time is 11 hours, 26 minutes which is 46 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) began two 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. Palm Sunday is in two days. -Bernie-