June 1: ORD

Today is June 1st. It's the 152nd day of the year. 213 days remain. It's week 22 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 75 and the normal low is 53. I've calculated the 32-year averages at 77 and 54.

On the hot side, in 1988 the high was 93 with a low of 60, a 33 degree spread. In 2002 the high was 92 with a low of 60, a 32 degree spread. Another warm low was 65 in 1987. The record high of 102 and record warmest low of 74 were set on the same hot day back in 1934. 24 of the past 32 highs (75%) were in the: 70s (12) and 80s (12). Two highs were in the warmer 90s. Six highs were in the cool 60s. Our most recent 60s high was 63 in 2003. O'Hare has not recorded a high of 87, 88 or 89 on this day (80s that are significantly above normal). There have been four highs of 85 degrees and three of 86 degrees in the last 32 years. Most recently, the high was 85 degrees last year (in 2010) and in 2007.

Yesterday (May 31, 2011) was the second warmest May 31 at O'Hare. The high of 85 and low of 69 was just a degree cooler than the warmest day which occurred two decades earlier in 1991 (high of 89, low of 67).

In looking back through the years to the first June at O'Hare in 1959, the following instances were notable: In 1972 the high was 80 with a low of 49, a 31 degree spread. In 1970 the high was 75 with a warm low of 68, a seven degree spread. In 1966 the low was a cold 40 degrees. In 1964 the low was a cold 41 degrees. In 1963 the high was 85 with a low of 55, a 30 degree spread. In 1961 the low was a warm 68 degrees.

More recently, there were large spreads of 38 degrees in 1986 (86/48), 34 degrees in 1984 (83/49) and 30 degrees in 2005 (80/50).

On the cool side, in 2003 the high was 63 with a low of 38. A decade earlier, in 1993, the high was 64 with the record low of 37. Another cold low was 41 in 1983. Another cool high was 62 in 1994. The record coolest high of 48 occurred in 1946. 24 of the last 32 lows (75%) were in the: 50s (14) and 60s (10). Eight lows were in the cold: 30s (2) and 40s (6). Our most recent 40s low was 49 in 2001.

The past seven years (2004-2010) have followed the normal pattern of a high in the 70s or 80s and a low in the 50s or 60s. It is interesting to note that our most recent 90s high (92 in 2002) was followed by our most recent 60s high (63 in 2003).

The following astronomical data is provided by the United States Naval Observatory. In Crystal Lake, twilight begins at 4:46 and sunrise is at 5:20. Sunset is at 20:23 and twilight ends at 20:57. There's a total of 15 hours, 3 minutes of daylight today and 16 hours, 11 minutes between twilights. We gained a minute of daylight from yesterday. Tomorrow twilight begins at 4:45 and sunrise is at 5:19. The moon will be new today at 16:03. Illumination was 0% at midnight, will be 0% at noon and 0% at midnight tonight. Moonrise is at 4:58 this morning. Moonset is at 20:31 tonight. Moonrise is at 5:48 tomorrow morning. Moonlight time is 15 hours, 33 minutes which is 14 minutes longer than yesterday.

The warm part of Spring (Warm Spring) began 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. Flag Day is in 13 days.