SUBJECT: Warmest September in 50 years Saint Cloud September 1998 weather summary September 1998 in Saint Cloud was an extremely warm month. The average temperature of 62.9 degrees for the month was more than 5 and 1/2 degrees above normal, making September 1998 the warmest September since 1948 and placing this September 14th warmest out of the 119 years on record. Most of the warmth came from high temperatures, which averaged over 8 degrees above normal. Two record daily highs were tied and there were three days with highs of at least 90 degrees. This is the most number of 90-degree high temperatures since 1978, which had 7 days (the all-time record). Also, it makes for a rather strange warm season of 90+-degree highs. There were 8 days this warm season with a high of 90+, but only 2 took place during the meteorological summer (both in July). May had 3 90+ highs and September did likewise. The only other year I could find with more 90+ highs outside of the normal warmest months than during the normal summer was in 1978. Still, we had only 8 90+ high days, which is 2 days below normal. This continues the trend in the 1990's. Only 1995 has had at least 10 90+-days during the year. Actually, September 1998 could have been even warmer. During the first 19 days of September, the average temperature was 67.0 degrees, which would have been the warmest September of all time. The average high for the first 19 days was 82.0 degrees which is higher than the average high for any summer month. However, two periods of cooler air surges dropped 1998 out of the top 10. Rainfall was relatively scarce in September 1998. Only 1.25 inches fell, a little more than a third of the normal rainfall. It would have been one of the 10 driest Septembers on record if not for the .41 inches which fell with the cold front on the 30th. The dry conditions kept the soil dry, enabling strong sunshine to raise the high temperature substantially, despite some cool mornings. The low September rainfall total continues the '90's trend of dry Septembers. Seven of the 9 '90's Septembers have had less than normal rainfall and 5 of these years have had less than 2 inches of rain. However, this could be seen as counteracting the '80's trend in which 5 of the 10 years had September rainfall between 4.3 and 9.4 inches. SUMMARY FOR SEPTEMBER 1998 SEP 1998 NORMAL TEMPERATURE Average high temperature ( F) 77.2 69.1 Average low temperature ( F) 48.6 45.4 Average temperature ( F) 62.9 57.3 Warmest high for this month ( F) 92 on the 19th Coolest high for this month ( F) 58 on the 21st, 30th Mildest low for this month ( F) 64 on the 12th Coldest low for this month ( F) 32 on the 22nd Records broken: Daily warm high 91 (tie) on the 13th (previously in 1927, 1939) 88 (tie) on the 18th (previously in 1984) PRECIPITATION (in) September 1.25 3.14 Greatest in 24 hours (Sept 1998) .41 on the 30th ============================================================================= Bob Weisman, Meteorology Professor SUPERVISOR: Shirley (age 6) Earth Sciences Department PHONE: (320) 255-3247 MS 48 FAX: (320) 255-4262 Saint Cloud State University EMAIL: scsweisman@tigger. 720 4th Avenue South stcloudstate.edu Saint Cloud, Minnesota 56301-4498 (car radio on with Dad's voice on station) Shirley: How did you get on the radio? Dad: They called me up and asked me questions. Shirley (while Dad's voice is still on, changes the station) ===============================================================================
mcwg@soils.umn.edu