April 10: ORD

Today is April 10th. It's the 100th day of the year. 265 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 56 and the normal low is 36. I've calculated the 32-year averages at 55 and 34.

On the warm side, in 2005 the high was 79 with a low of 44, a 35 degree spread. In 1981 the high was 69 with a low of 50. Six years later, in 1987, the high was 74 with a low of 45. In 1992 the high was 69 with a low of 46. Other warm highs were 74 last year (in 2010) and 71 five years ago in 2006. The record high of 90 was set back in 1930. The record warmest low of 55 occurred back in 1945. 23 of the last 32 highs (72%) were in the: 40s (11) and 50s (12). On the warmer side, nine highs (28%) were in the: 60s (5) and 70s (4). Today's high is predicted to be off the charts, somewhere in the 80s and then followed by severe weather. The only time O'Hare was in the 80s was in 1977 (see next section). Today's low may also be off the charts, somewhere in the 60s. If this is the case, a new record warmest low will also be established today.

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 85 with a low of 50, a 35 degree spread and warm day. In 1976 the high was a warm 72 with a low of 37, a 35 degree spread. In 1975 the high was a cold 44 degrees. In 1973 the high was a cold 35 with a low of 28, a seven degree spread and cold day. In 1971 the high was a warm 69 with a low of 32, a 37 degree spread. In both 1960 and 1966 the lows were a cold 24 degrees. In 1959 the high was a cold 38 with a low of 28, a cold day.

More recently, we had a small spread of seven degrees in 2000 (40/33). The large spreads were more numerous: 37 degrees in 2006 (71/34), 36 degrees last year (in 2010) (74/38), 32 degrees in 1996 (62/30), 32 degrees in 2003 (58/26), 31 degrees in 1986 (60/29) and 30 degrees in 2002 (64/34).

On the cold side, in 1989 the high was 40 with the record low of 18. In 1997 the high was 40 with a low of 21. In 1980 the high was 40 with a low of 29. Other cold highs were 40 in 2000, 41 in 1995, 43 in 1982 and 44 in 1983. The record coldest high of 32 occurred way back in 1892. 17 of the last 32 lows (53%) were in the 30s. Nine lows (28%) were in the cold: 10s (a.k.a. teens) (1) and 20s (8). Six lows (19%) were in the warmer: 40s (5) and 50s (1).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 5:52 and sunrise is at 6:21. Sunset is at 19:29 and twilight ends at 19:58. There's a total of 13 hours, 8 minutes of daylight today and 14 hours, 6 minutes between twilights. We gained three minutes of daylight from yesterday. Tomorrow twilight begins at 5:51 and sunrise is at 6:20. The moon is waxing crescent, heading towards first quarter tomorrow at 7:05. Illumination was 37% at midnight, will be 42% at noon and 47% at midnight tonight. Moonset was at 1:30 this morning. Moonrise is at 10:59 later this morning. Moonset is at 2:13 tomorrow morning. Moonlight time is 14 hours, 31 minutes which is 13 minutes shorter than yesterday.

The warm part of Spring (Warm Spring) begins in three days 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. Palm Sunday is in seven days. -Bernie-