NOAA: Near-Normal U.S. Temperatures and Above-Normal U.S. Precipitation in May
June 8 , 2010
NOAA’s State of the Climate report shows the May 2010 average temperature for the contiguous United States was 60.8 degrees F, which is 0.2 degrees F below the long-term (1901-2000) average. May’s average precipitation was 3.10 inches, 0.23 inch above the 1901-2000 average.
Based on a 116-year record dating back to 1895, this monthly analysis prepared by scientists at NOAA’s National Climatic Data Center in Asheville, NC, is part of the suite of climate services NOAA provides.
U.S. Temperature Highlights
- Warmer-than-normal temperatures in the eastern U.S. were offset by cooler-than-normal temperatures in the west, creating a national temperature near the long-term average.
- The Northeast and Southeast regions had their 10th warmest May on record, while the Northwest and West had their fifth and 10th coolest May, respectively.
- On the state-to-state level, Rhode Island and Florida (tied) each experienced their second warmest May on record. Louisiana experienced its fourth warmest, Massachusetts its fifth warmest, Connecticut its sixth warmest, New Hampshire its seventh warmest, Mississippi and New York their eighth warmest and New Jersey its ninth warmest May.
- By state, several experienced cooler average temperatures. This was Idaho’s second coolest May on record, Montana’s fourth, Wyoming and Oregon’s seventh coolest, Utah’s eighth, California’s ninth and Nevada’s 10th.
- The spring season (March-May) brought record warmth to the Northeast. Eight northeastern states experienced their warmest March-May period on record: Connecticut, Rhode Island, Maine, Massachusetts, New Hampshire, New Jersey, New York and Vermont. Michigan also had its warmest spring period of the 116-year record.
- The profound warmth in the Northeast has dominated throughout 2010 so far. Maine, New Hampshire and Vermont each averaged their warmest January-May on record. Warm conditions also prevailed in Massachusetts and Rhode Island which had their second warmest January-May period. The year-to-date has been significantly warm in other states, including: New York (third warmest), Connecticut and Michigan (fourth warmest), Wisconsin (fifth warmest) and New Jersey (eighth warmest). Conversely, January-May 2010 has been among the 10 coolest for Florida, Alabama and Georgia.
U.S. Precipitation Highlights
- May precipitation was variable across the contiguous U.S., averaging slightly above normal. The state of Washington had its third wettest May on record, Kentucky its seventh and North Dakota its 10th wettest. Extreme precipitation events in Tennessee led to its sixth wettest May on record. Louisiana had its fifth driest March-May period on record. Rhode Island had its second wettest spring and Massachusetts its 10th wettest.
- The spring season (March-May) brought the fifth driest period on record for Louisiana, while Rhode Island had its second wettest and Massachusetts its 10th wettest.
- Dryness in Michigan and Louisiana has persisted throughout 2010, becoming the fifth driest January-May on record for both states. The year-to-date period was also the sixth driest for Wisconsin. Conversely, very high precipitation during February and March contributed to Rhode Island’s fifth wettest year-to-date period. Massachusetts also averaged much above normal precipitation, with its 10th wettest such period.
- A storm system that stagnated over the Lower Mississippi Valley May 1-2 killed 29 people and flooded thousands of homes and businesses. The storms spawned dozens of tornadoes and brought record amounts of rain to numerous locations in Mississippi, Tennessee and Arkansas. Preliminary reports indicated that more than 200 daily, monthly and all-time precipitation records were broken across the three states. More details can be found within NCDC's Global Hazards page.
Other Highlights
- For the second consecutive month, the snowcover footprint over North America was the smallest on record for the month. A record-small snow footprint was also observed over Eurasia and the Northern Hemisphere as a whole.
- NCDC’s Climate Extremes Index (CEI) for spring (March-May) was about 5 percent higher than average. The CEI measures the occurrence of several types of climate extremes (like record or near-record warmth, dry spells, or rainy periods). Factors contributing to spring’s elevated values include: widespread (up to three times larger than average) coverage of anomalously warm high and low temperatures and above-average extent of extreme one-day precipitation events.
- According to NOAA’s Storm Prediction Center, tornadic activity in May was near normal with 290 preliminary tornado reports.
- Drought coverage decreased slightly in May. The U.S. Drought Monitor reported 8.6 percent of the United States was affected by drought at the end of May, a decrease from April. Slight improvements were seen in the Tennessee and Ohio River valleys, while conditions deteriorated in Louisiana and Michigan.
- The cool conditions across the western U.S. contributed to the low numbers of new wildfires during May. Only 5,159 new wildfires were reported during the month – the lowest May number in 11 years.
NCDC’s State of the Climate reports, which assess the current state of the climate, are released soon after the end of each month. These analyses are based on preliminary data, which are subject to revision. Additional quality control is applied to the data when late reports are received several weeks after the end of the month and as increased scientific methods improve NCDC’s processing algorithms.
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