Global temperatures in September were eighth warmest on record

The Earth experienced its eighth warmest September since record keeping began in 1880. The annual minimum Arctic sea ice extent was reached on September 9 and ranked as the second smallest extent since satellite records began in 1979.

This monthly analysis from NOAA’s National Climatic Data Center is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

Global Temperature Highlights: September

· The combined global land and ocean average surface temperature for September was the eighth warmest on record at 59.95 degrees F (15.53 degrees C), which is 0.95 degrees F (0.53 degrees C) above the 20^th century average of 59.0 degrees F (15.0 degrees C). The margin of error associated with this temperature is +/- 0.20 degrees F (0.11 degrees C).

· Separately, the global land surface temperature was 1.57 degrees F (0.87 degrees C) above the 20^th century average of 53.6 degrees F (12.0 degrees C), making this the fourth warmest September on record. The margin of error is +/- 0.43 degrees F (0.24 degrees C). Warmer-than-average conditions occurred across Europe, northern and western Africa, western Russia, the western and northeastern United States, Canada, and Mexico. Cooler-than-average regions included much of eastern Asia, and part of the central United States.

· The September global ocean surface temperature was 0.72 degrees F (0.40 degrees C) above the 20^th century average of 61.1 degrees F (16.2 degrees C), making it the 14^th warmest September on record. The margin of error is +/- 0.07 degrees F (0.04 degrees C). The warmth was most pronounced across the north central and northwest Pacific Ocean and within about the 30°N–40°N latitude belt across the Atlantic.

· The United Kingdom marked its warmest September since 2006 and sixth warmest in the last 100 years, at 2.7 degrees F (1.5 degrees C) above the 1971–2000 average.

· Spain had its warmest September since 1990 and fifth warmest for the past 50 years, at 3.2 degrees F (1.8 degrees C) above the 1971–2000 average.

Global Temperature Highlights: Year to date

· The combined global land and ocean average surface temperature for the January – September period was 0.94 degrees F (0.52 degrees C) above the 20^th century average of 57.5 degrees F (14.1 degrees C), making it the 11^th warmest such period on record. The margin of error is +/- 0.18 degrees F (0.10 degrees C).

· The January – September worldwide land surface temperature was 1.44 degrees F (0.80 degrees C) above the 20^th century average — the seventh warmest such period on record. The margin of error is +/- 0.36 degrees F (0.20 degrees C). The global ocean surface temperature for the year to date was 0.74 degrees F (0.41 degrees C) above the 20^th century average and was the 12^th warmest such period on record. The margin of error is +/-0.07 degrees F (0.04 degrees C).

· La Niña conditions strengthened during September. According to NOAA’s Climate Prediction Center, La Niña is expected to gradually strengthen further and continue into the Northern Hemisphere winter 2011/12.

Polar Sea Ice and Precipitation Highlights

· Arctic sea ice reached its annual minimum extent on September 9 at 1.67 million square miles (4.33 million square km), marking the second smallest extent on record. In September 2007, the sea ice extent dipped to 1.61 million square miles (4.17 million square km). According to the University of Washington’s Polar Science Center, Arctic sea ice volume, which depends on ice thickness and extent, dropped to 960 cubic miles (4,000 cubic km) on September 10, the smallest volume on record.

· The average Arctic sea ice extent for the month was 34.5 percent below average, ranking as the second smallest September extent since satellite records began in 1979. The extent was 938,000 square miles (2.43 million square kilometers) below average and 120,000 square miles (310,000 square kilometers) above the record low September extent set in 2007.

· On the opposite pole, sea ice extent typically reaches its annual maximum extent during September, but environmental conditions extended the ice growth season into October. The September Antarctic monthly average extent was 0.9 percent above the 1979–2000 average, the 14^th largest (19^th smallest) on record.

· September brought a mix of wet and dry conditions around the globe. Tropical cyclones Talas and Roke impacted Japan and nearby regions with intensive precipitation; Nesat brought extremely heavy rainfall to the Philippines; and Irene and Lee drenched the northeastern United States. Irene also dumped heavy rain over the Dominican Republic. The southwest Asian monsoon brought heavy precipitation to Pakistan and eastern India. Other regions with much higher-than-normal precipitation included Colombia in South America and part of southeastern Africa around Mozambique, Zimbabwe, and Tanzania.

· Below-average precipitation anomalies across the southern tier of the United States are indicative of an ongoing major drought conditions. It was also exceptionally dry across the western United States, much of eastern and southern South America, particularly eastern Brazil, much of central Asia, including nearly all of Mongolia, and much of Australia.

· Spain experienced a much drier than normal September, with average rainfall across the country (16 mm / 0.63 in) about one-third of normal, making this month the driest September since 1988.

Good Hay Cutting Pattern... Yes, But Not As Good As You Think

After such a wet weather pattern, a lot of farmers are getting antsy to get out and cut some hay. For those who don't know about farming, the hay needs to dry before bailing. Moisture can cause a plethora of problems if it's in a bail of hay, including causing the hay to decompose at a high enough temperature to cause the hay to combust. So at this point, I hopefully have convinced you that we do need dry weather.

Many farmers look at 7 day forecasts to find the dry weather. They look for a period of at least 3 sunny days for the best conditions. While this practice works most of the year, when we head into October, that's not quite the case. Normally sunny weather means being under a center of high pressure. The center of high pressure also means little in the way of wind. With a clear sky and light winds, along with the longer nights at this time of the year, this is the prime set up for the formation of fog and dew. Even with the sunshine this time of the year, that's moisture that needs to evaporate and it takes longer than the other times of the year with a lower sun angle.

Earth Gauge Tip - Planting Trees

Did you know that planting one oak tree in your yard can save you money? A new oak sapling (one-inch in diameter) will save about 29 dollars over one year. Much of that money comes from the increase in property value that a tree provides, but your new tree will also absorb about 80 gallons of rain water runoff, improve air quality and reduce your energy bill. When your tree grows to six-inches in diameter, it will provide about 75 dollars in benefits each year!

This is a great time of year to add a tree to your yard. In the northeastern United States, new trees can be planted until early October. Cooler temperatures and rainfall help new trees establish healthy roots that will support new growth when spring rolls around next year.

• Find recommended native plant and tree species our area: www.wildflower.org/collections/
• Calculate the benefits of planting other types of trees: www.arborday.org/calculator/.