The Climate Prediction Center (CPC) forecast for June of enhanced probabilities of above normal temperatures and below normal precipitation for Tucson was accurate. The average monthly temperature of 86.3° goes into the record books as the 10th warmest June on record. The warmer than normal June ended a run of four consecutive months of below normal temperatures. Although monsoonal moisture started working its way into southeast Arizona during the last ten days of the month, the airport did not record a drop of rain during June.

The month started off with temperatures in the mid to upper 90s, then were between 100 and 106 degrees from the 5th through the 10th. An unseasonably cool upper level trough moved into the desert southwest between the 11th and 14th. This feature brought much below normal temperatures to the area on the 12th and 13th with highs only in the upper 80s. This marked the first time since 1999 that Tucson recorded consecutive days with highs in the 80s in June. Additionally, these temperatures in the 80s happened over a weekend (Saturday/Sunday) which is the first time that has happened in Tucson since 1997 (7th/8th). Looking back at the historical record, dating back to 1895, this was also the 15th June weekend that the highs were cooler than 90 degrees.

Starting on the 15th through the end of the month, daily highs were above 100 degrees peaking on the 23rd when the airport recorded a high of 109°. Overnight low temperatures during this time frame were mostly in the upper 60s to upper 70s. The exceptions were 81° on the 25th and 29th and a very warm 84° on the 30th. The low on the 30th ranks at the 5th warmest daily low temperature on record for June and 27th all-time warmest daily low. The all-time warmest daily low is 89° which occurred on July 22, 2006.

Temperature extremes for the month ranged from a high of 109° on the 23rd to a low of 60 degrees on the 13th. The monthly average temperature of 86.3 degrees is 2.2 degrees above normal. Two temperature records were tied during June and both of them were high minimum temperature. The first one occurred on the 9th (76°, tied record of 76° previously set in 1996) and the second one occurred on the 25th (81°, tied record of 81° previously set back in 1970).

Overall, most of the Tucson metro area did not record any rain during June. The Tucson International airport did not record any rain and will go into the record books as the 14th June, first since 2002, with ZERO rainfall. The 30-year normal is near a quarter of an inch /0.24"/.

The much above normal June and pushed the 2010 average temperatures to slightly above normal (see table below). Only three temperature records (one low maximum and two high minimums) has been set/tied during 2010. This is the first time since 1998, and 11th time overall (1998/1995/1979/1977/1973/1966/1964/1961/1945/1941), that no record HIGHS have been set/tied through June. Although the airport hasn't measured any rain since May 2nd, a stretch of 59 days (28th longest streak on record), the 2010 rainfall total at the airport of 4.76", thanks to a very wet winter, ranks as the 16th wettest (tied with 1987) January thru June period on record.

Climatic normals describe the average of a meteorological value, like temperature and precipitation, over a 30 year period. The United Nations World Meteorological Organization (WMO) established guidelines that climatic normals be calculated using three consecutive 10-year periods ending in the most recent year that ends with the digit 0. 2010 marks the last year for collecting the latest 10-year period that will be used for the new 30-year normals. The National Climatic Data Center (NCDC) will be calculating these new 1981-2010 normals during 2011 and they will go into effect in 2012.

The following table shows the June differences between the 2001-2010 period versus the 1971-1980 period that it will replace.

This next table compares the preliminary 1981-2010 normals versus the current 1971-2000 normals. The 1981-2010 data shown below will not be the actual values that NCDC (National Climatic Data Center) derives, but they are a very close approximation.

Glueck