Hurricane Debby and summer storms drive rainfall above monthly average

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Map of Florida rainfall summary data
Map of Florida rainfall summary data

A map illustrates rainfall conditions in August across the St. Johns River Water Management District.

PALATKA, Fla., Sept. 16, 2024 — August rainfall marked a return to above-average levels across much of the St. Johns River Water Management District region. Early in the month, Hurricane Debby brought significant rain to northern and western counties, with typical summer rain patterns contributing throughout the rest of August. Thirteen of the District’s 18 counties reported rainfall totals above their monthly averages, with northern and western areas seeing the most substantial amounts.

A full report outlining August’s hydrologic conditions was presented at the District’s Governing Board meeting. Highlights include:

Rainfall

  • Districtwide average rainfall was 8.43 inches, 1.43 inches above the monthly average.
  • County-wide monthly rainfall totals ranged from a high of 13.89 inches in Nassau County to a low of 6.15 inches in Volusia County.
  • Cumulative rainfall for the past 12 months was 54.03 inches, 3.02 inches above the long-term average.
  • Thirteen counties are now above their annual average, with Nassau County 13.5 inches above its annual average.

Groundwater

  • The Upper Floridan Aquifer showed a strong increasing trend in August, with most areas now in the normal range and some along the western boundary moving into the high range.
  • Districtwide groundwater levels, expressed as a single index, were in the 63rd percentile, normal for this time of year.

 

Spring flows

  • Silver Springs recorded a mean monthly flow of 676 cubic feet per second (cfs), or 437 million gallons per day (mgd), a 108 cfs increase from July, remaining in the normal range for this time of year.
  • Blue Spring station in Volusia County reported a mean monthly flow of 147 cfs (95 mgd), also within the normal range.
  • Rock Springs saw a slight increase, remaining in the normal range at 59 cfs (38 mgd).
  • Wekiwa Springs recorded a mean monthly flow of 62 cfs (40 mgd), also in the normal range for this time of year.