September 2006 Saint Cloud Weather Summary

September 2006 in Saint Cloud continued to contribute to our "drought-busting" weather. Total rainfall at the Saint Cloud Regional Airport was 5.09 inches, more than two inches above the normal total of 5.09 inches. However, the rainfall total only ranks as the 16th wettest September of the 114 years of Saint Cloud rainfall records. In fact, wet Septembers have become the rule in recent years. Only 4 years ago, September rainfall was 6.67 inches, the 4th wettest September (see 10 wettest Septembers in Saint Cloud history) Also, September rainfall was well over 5 inches in both 2004 and 2005 (see historic Saint Cloud rainfall). The record September rainfall is over 10 inches of rain, set in 1926.

However, the last month has made a dramatic difference in our water table. Since August 23, the Saint Cloud Regional Airport has picked up 7.96 inches of rain, nearly four inches above the normal amount of 4.05 inches. In more than three months before the rains started (May 15-August 22), Saint Cloud only had 6.00 inches of rain, which was nearly six and a half inches below normal. It has been odd that we have picked up nearly all of the rain in three big doses: 2.87 inches on August 23-24, 3.00 inches on September 2-3, and 1.56 inches on September 21-23. The two big September rains accounted for 4.56 inches of the 5.09 inches total or almost 90% of the September total. The heavy rain did set a daily record for rainfall on September 3 with 1.61 inches of rain on September 3rd.

Even though the storms of September 16 only produced 0.33 inch of rain in Saint Cloud, that date did produce a tornado that moved through several housing developments in Rogers, killing one 10-year-old boy and injuring people (NWS Summary of Rogers Tornado)

The reason for these heavy rain events is that the Upper Midwest has been dominated by strong, slow-moving storms that have intensified over the Dakotas, Minnesota, Iowa, and/or Wisconsin. The slow movement of these storms, rather than producing fast-moving spotty thunderstorms as was true during much of the summer, have had plenty of time to produce repeated showers and thunderstorms over large parts of Minnesota. The slow movement also meant that there were two or three days with a high chance of rainfall, rather than the one-day shots we had earlier in the summer.

The net effect of all of this rain can be seen in the National Drought Mitigation Center's US weekly drought monitor loop. Central Minnesota has gone from an extreme drought condition in early to middle August to normal moisture conditions now. In addition, the rainfall on September 21-23 was particularly important for the state of Minnesota since there was finally significant rain in north center and northeastern Minnesota, an area still hard hit by the dry conditions (see the the latest Minnesota State Climatology Office's 2006 dry summer update.

With all of the recent clouds and cool temperatures, it may have felt like we were headed for a much cooler than normal September. However, the Saint Cloud average September temperature was 56.5°F, only 0.9°F cooler than normal. The impression that the days have been chilly does have some support. High temperatures are averaging more than two degrees cooler than normal (avg. high: 67.2°F; normal high: 69.0°F), but all of the clouds have kept our low temperatures near normal (avg. low: 45.9°F; normal low: 45.7°F). On the other hand, September 2006 is the coolest September we've had since 1995. That's because we have been used to some very mild Septembers as average temperatures have been 4-7 degrees warmer in three of the past four Septembers (historic Saint Cloud monthly temperatures since 1993). The last September that was nearly this cool was September 1995. The September Saint Cloud records show another quality of September 1995: it had the earliest measurable snowfall in Saint Cloud history happened on September 21, 1995.

However, note that the weather for the first two days of October will be a marked contrast to September with highs well into the 70's on Sunday and perhaps in the 80's on October 2.

    September 20 did produce the first frost of the year at the Saint Cloud Airport. The average date of the first frost in September 22. You can check the Minnesota median first/last frost dates from the Minnesota State Climatology Office.

    September 2006 Statistics