April 25: ORD

Today is April 25th. It's the 115th day of the year. 250 days remain. It's week 17 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 62 and the normal low is 41. I've calculated the 31-year averages at 65 and 42.

On the warm side, in 1990 the high was the record high of 87 with a low of 66. You are seeing double! The temps in 1990 were the same for the 24th and the 25th. Four years later, in 1994, the high was 85 with a low of 59. In 1979 the high was 73 with a low of 61. In 1986 the high was 75 with a low of 56. Other warm highs were 82 two years ago and 77 last year. Another warm low was 54 in 1996. The record warmest low of 68 was set in 1915. 19 of the last 31 highs were: 60s (11) and 70s (8). On the warmer side, three highs were in the 80s. On the cooler side, nine highs were: 40s (4) and 50s (5). As a post script, last year's high at O'Hare was 77 at 14:42 with a low of 41 at 23:33. This produced a mean of 59 which puts the day eight warmest of the past 31 years. It would've finished warmer had it not been for an afternoon cool off. Winds shifted from the southwest to the northeast. This caused the following temperature drops: O'Hare went from 66 at 16:00 to 44 at 17:00; Midway went from 69 to 48 at the same time; West Chicago (DuPage County airport) went from 69 at 16:00 to 59 at 17:00 to 48 at 18:00. Rockford's drop-off was more gradual.

In looking back through the years to the first April at O'Hare in 1959, the following instances were notable: In 1976 the high was a cold 45 with a low of 36, a cold day. In 1974 the high was 66 with a low of 36, a 30 degree spread. In 1972 the high was a cold 50 with a low of 31, a cold day. In 1971 the high was 68 with a low of 37, a 31 degree spread. In 1970 the high was 76 with a low of 54, a warm day. In 1969 the high was 72 with a low of 41, a 31 degree spread. In 1967 the high was 52 with a low of 28, a cool day. In 1966 the high was 73 with a low of 39, a 34 degree spread. In 1962 the high was 84 with a low of 56, a warm day. In 1961 the high was 45 with a low of 40, a five degree spread.

More recently, we had a small spread of four degrees three years ago (49/45). We had large spreads of 30 degrees in 1985 (71/41), 30 degrees in 1999 (63/33), 31 degrees in 1984 (70/39), 32 degrees in 1988 (70/38) and 43 degrees in 1983 (71/28).

On the cold side, in 1980 the high was 46 with a low of 30. In 2006 the high was 46 with a low of 32. Another cold low was 28 in 1983. Other cold highs were 47 in 1992 and 49 three years ago. That low of 28 in 1983 was the low point of a day which saw a high of 71. The record low of 27 was set way back in 1887. The record coldest high of 40 was set back in 1910. 24 of the last 31 lows were: 30s (13) and 40s (11). One low was in the colder 20s. Six lows were in the warmer: 50s (4) and 60s (2).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight began at 5:27 and sunrise was at 5:57. Sunset is at 19:46 and twilight ends at 20:16. There's a total of 13 hours, 49 minutes of daylight today and 14 hours, 49 minutes between twilights. Tomorrow twilight begins at 5:26 and sunrise is at 5:56. The moon is waxing gibbous. Illumination was 86% at midnight, will be 90% at noon and 93% at midnight tonight. Moonset was at 4:01 this morning. Moonrise is at 16:52. Moonset is at 4:28 tomorrow morning. Moonlight time is 11 hours, 9 minutes which is 48 minutes shorter than yesterday.

- Bernie -