The planet’s ocean surface temperature was the warmest on record for July, breaking the previous high mark established in 1998 according to an analysis by NOAA’s National Climatic Data Center. The combined average global land and ocean surface temperature for July 2009 ranked fifth-warmest since world-wide records began in 1880.
- The global ocean surface temperature for July 2009 was the warmest on record, 1.06 °F (0.59 °C) above the 20th century average of 61.5 °F (16.4 °C). This broke the previous July record set in 1998. The July ocean surface temperature departure of 1.06 °F from the long-term average equals last month’s value, which was also a record.
- The global land surface temperature for July 2009 was 0.92 °F (0.51 °C) above the 20th century average of 57.8 °F (14.3 °C), and tied with 2003 as the ninth-warmest July on record.
- The combined global land and ocean surface temperature for July 2009 was the fifth warmest on record, at 1.03 °F (0.57 °C) above the 20th century average of 60.4 °F (15.8 °C).
Notable global developments and events for the month included:
- El Niño persisted across the equatorial Pacific Ocean during July 2009. Related sea-surface temperature (SST) anomalies increased for the sixth consecutive month.
- Large portions of many continents had substantially warmer-than-average temperatures during July 2009. The greatest departures from the long-term average were evident in Europe, northern Africa, and much of western North America. Broadly, across these regions, temperatures were about 4-7 °F (2-4 °C) above average.
- Cooler-than-average conditions prevailed across southern South America, central Canada, the eastern United States, and parts of western and eastern Asia. The most notably cool conditions occurred across the eastern US, central Canada, and southern South America where region-wide temperatures were nearly 4-7 °F (2-4 °C) below average.
- Arctic sea ice covered an average of 3.4 million square miles during July. This is 12.7% below the 1979-2000 average extent and the third-lowest July sea ice extent on record, behind 2007 and 2006. Antarctic sea ice extent in July was 1.5% above the 1979-2000 average. July Arctic sea ice extent has decreased by 6.1% per decade since 1979, while July Antarctic sea ice extent has increased by 0.8% per decade over the same period.
US highlights for July 2009 included:
- For the contiguous United States the average July temperature of 73.5 °F (23.1 °C) was 0.8 °F (0.4 °F) below the 20th century average and ranked as the 27th coolest July on record, based on preliminary data.
- Four of the seven states that make up the Central US (Ohio, Illinois, Indiana, and West Virginia) experienced their coolest ever July in 115 years of records. The region’s three remaining states of Kentucky, Missouri, and Tennessee recorded either their second or third coolest July in history. Pennsylvania also experienced a record cool July, while Wisconsin and Michigan each had its second coolest on record.
- Three western states recorded an average temperature that was much above normal for the month of July: Arizona experienced its third warmest, while New Mexico and Washington each had its ninth warmest July on record. Death Valley, California set its all-time monthly average maximum temperature of 121.3 °F (49.6 °C). Twenty-two days in Death Valley reached 120 °F (48.9 °C)or higher which beat the old record of 19 days.
- This was the 40th wettest July in the 1895—2009 record. Precipitation across the contiguous US averaged 2.90 inches (74 mm), which is 0.14 inch (4 mm) above the 1901-2000 average.
- For the contiguous US as a whole, precipitation was near normal. The above normal averages in the Central and Northeast were counter-balanced by the below normal averages in the Southeast, Southwest, and East North Central regions.
- Massachusetts and Rhode Island both experienced their second and Arkansas its third wettest July on record. Several other states were much above normal including: Maine which experienced its fifth wettest, and Vermont, New Hampshire, and Connecticut each recorded their sixth wettest month.
- Based on the Palmer Drought Index, severe to extreme drought affected about 11% of the contiguous United States as of the end of July 2009, an increase of about 5% from last month. About 17% of the contiguous US fell in the severely to extremely wet categories. About 19% of the contiguous US fell in the moderate to extreme drought categories (based on the Palmer Drought Index) at the end of July.
State of the Climate. National Oceanic and Atmospheric Administration National Climatic Data Center Monthly Reports