The dry period that began in early summer intensified across Minnesota during September. 根据St. Cloud Regional Airport, the 2012年9月 rainfall totalled only 0.24英寸，3英寸.比正常低02英寸. 这使得2012年9月成为St. Cloud's 九月是圣. 云记录. The only drier September was recorded in 1952 when only 0.07英寸下降. 1952 was also the last year in which no September day had at least 0.10英寸的雨.

Largest Partial Growing Season Rain Shortfall Since 1988

The very dry conditions have come since the wet spring mostly ended in May. 6月1日至9月30日期间，圣. 云只获得了7个.41英寸的降雨量. 四个月平均降雨量为14.73 inches. While three of the past 4 growing seasons have had some kind of dry spell during the growing season, the 7.32 inch deficit in the past 4 months is the largest deficit and the worst than any single growing season since our last major drought in 1986-1989. In fact, June-Sept 2012 has had the third 六月至九月雨量最少 in St. 云记录. The last year the summer and early fall was drier than this year was in 1950 when only 5.在这四个月里下降了30英寸.

So far in October, the dry conditions have worsened. There has been no measurable rainfall in St. 云到10月12日，所以圣. Cloud rainfall deficit since June 1 totals 8.44 inches. 根据 weekly drought report from the 明尼苏达州 Climatology Office, some of the largest rainfall deficits statewide are being seen in a 明尼苏达州中部地带 running from Lac qui Parle through Glenwood, Benson, Willmar, Atwater, Paynesville, Annandale, 进入埃尔克河. Rainfall deficits since the start of June are running 7-10 inches since mid-June. Thus, all of central Minnesota is now being listed in the severe drought category by this week's 美国干旱监测. Still, the worst conditions are in northwestern Minnesota, which missed the 春雨滂沱和明尼苏达州西南部. These dry conditions could push the ranking of the summer-fall 2012 to near the top of the driest single seasons. 在这个月的最后19天，圣. Cloud would have to pick up more than 1.65 inches of rain to avoid beating 1950 as the year with the driest June-October period.

The very dry conditions, combined with a number of windy days, led to several outbreaks of wildfires. 最具破坏性的火灾 happened in Karlstad in northwestern Minnesota in early October. 许多火灾都是由 十月初的暴风雪 在明尼苏达州西北部，但是 一般干燥条件 elsewhere were causing problems during any warmer and breezy day.

The heavy spring rains, however, were enough to allow a near normal harvest of corn and soybeans. 地下水已经付出了代价, which must be replenished before we get too far into next spring's growing season.

Daily Temperature Roller Coaster Much Like a Desert

“沙漠般的”环境导致了 roller coaster of temperatures in September，通常在同一天. The average September temperature at the St. 云地区机场排名59.6华氏度，只有1.比正常温度高0°F. 然而，这是由75组成的.5°F平均高温(5.比平均温度高2°F)和43.平均低温(3.比平均温度低2华氏度). Nineteen of the 30 September days had at least a 30 degree difference between the high and low temperature with 4 days producing at least a 40 degree temperature difference.

The very dry conditions helped to produce those large ranges by reducing the average greenhouse effect. Water vapor is the most abundant greenhouse gas. 在干燥天气期间, there is less moisture in the air than average, meaning both that more sunshine gets to heat the ground during the day, 导致温度升高, and more earth energy goes directly out to space at night, 导致更冷的低温. While St. Cloud is not nearly as hot as Death Valley, note that the 平均范围 (difference between high and low temperature) during September in Death Valley is about 30-33 degrees, 差不多和 St. 九月的平均值.

34年来九月最高气温

实际温度确实下降了 9月还有两次90度， 2012年的总金额为 90度的天 到17天. That didn't quite make it to the 20 days seen in both 2006 and 2007. 其中包括 创记录的96度高温 9月11日. That was the latest in the year 90-degree high since 1998 (hit 90 on September 19) and the highest September temperature since 1978 (98 degrees on September 7). A second record was tied on 9月29日 with a high of 84 degrees.

The relatively cool nights did produce a nearly average date of first frost (9月22日, right on the average date) and first hard freeze (9月27日, average October 1)

2012年气温将破纪录

Through the first 9 months of 2012, the average St. 云温一直是52度.2°F. That's the warmest average for the first 9 months of the year. The previous high was a whole degree cooler (51.2°F)，设定于1931年. 请记住，圣. 云已经有了它的 warmest year defined by the heating season (2011年7月至2012年6月).

    2012年9月统计数据