If you think it was warmer than usual for July, you are correct. We recorded 21 days with high temperatures of 90° or greater. Last year we had 10. The average temperature for the month was 79.2° and although not making it to the century mark, we did reach 99° on July 19th. Another factor that made it unbearable at times was the high humidity. Dew point is a measure of the amount of moisture in the air and generally begins to feel somewhat uncomfortable when the dew point reaches 70° although each individual has his/her own comfort level. The heat and humidity are oppressive when dew points reach or exceed the upper 70’s. We had many days with dew points hovering around 80°. That, combined with temperatures in the low to mid 90s resulted in heat indices of 115 to 120° at times.
In addition to the heat, July will be remembered for a lack of rainfall. Total rainfall for the month was 2.00 inches. While not the driest recorded here, it was well below normal. The total monthly precipitation value does not always tell the whole story however, especially with regards to summer storms. I like to look at the days with 0.50 inch of rain or greater to get a better feel for how wet or dry a summer may have been. For this July we recorded only 1 day during the month when rainfall exceeded 1/2 inch. Most gardeners know that a typical garden needs around 1 inch per week during the summer. But in reality, that rarely occurs. Summer thunderstorms can produce rainfall rates that exceed 1 inch per hour so if you do get rain, it generally comes all at once. Chicago actually recorded the wettest July on record with a whopping 11.15 inches of rain! This was due to torrential rain that fell on July 23rd and deposited a calendar day total of 6.86 inches.
Here are some stats for the Goose Lake Weather station:
Averages\Extremes for the month of July 2011
Average temperature = 79.2°F
Average humidity = 76%
Average dewpoint = 70.3°F
Average barometer = 29.913 in.
Average wind speed = 1.4 mph
Average gust speed = 2.9 mph
Average direction = 165° (SSE)
Rainfall for month = 2.00 inches.
Maximum rain per minute = 0.04 in on day 24 at time 08:15
Maximum temperature = 99.2°F on day 19 at time 16:19
Minimum temperature = 58.0°F on day 09 at time 05:46
Maximum humidity = 100% on day 31 at time 07:50
Minimum humidity = 34% on day 08 at time 15:00
Maximum dewpoint = 83.1°F on day 28 at time 14:57
Minimum dewpoint = 53.1°F on day 07 at time 20:21
Maximum pressure = 30.09 in. on day 31 at time 08:41
Minimum pressure = 29.73 in. on day 20 at time 19:46
Maximum windspeed = 18 mph from 293°(WNW) on day 11 at time 08:12
Maximum gust speed = 28 mph from 293°(WNW) on day 11 at time 08:12
Maximum heat index = 122.0°F on day 21 at time 16:31
Avg daily max temp :90.5°F
Avg daily min temp :68.3°F
Total windrun = 1004.6miles
Here is an interesting graphic depicting the July 2011 departure from normal precipitation. The red circle is our location.