Buzzards Bay National Estuary Program

Buzzards Bay Climate Data, Historical Records, & Precipitation

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Sunrise - Sunset

Sunrise & Sunset for New Bedford, MA from the US Naval observatory:


MA DEM Rainfall Page: Data sets, advisories, drought information, and more

NOAA seasonal prediction for US temperature and precipitation

NOAA's Interactive Historical Weather Records for all sites
Data can be emailed to you for free.

NOAA's "unofficial" recent records for Massachusetts Cities
(Data is free, but not error checked [e.g., daily rainfall sometimes not recorded]. Great if you need to look up a specific month and year for a Massachusetts location.)

USGS hydrologic drought watch page
USGS hydrologic drought watch page

US Drought Monitor

Last months percent of monthly rainfall map
Last months percent of monthly rainfall map

2009-10 rainfall in Wareham versus 20-year average. Data from the Cranberry Experiment Station
2009-10 rainfall in Wareham versus 20-year average. Data from the Cranberry Experiment Station.

Daily Rainfall Data from the UMass Cranberry Experiment Station, East Wareham, 1988-1998 (Excel file)

Monthly Rainfall Data from the UMass Cranberry Experiment Station, East Wareham, 1988-2007 (Excel file)

Data from Cranberry Experiment Station Courtesy of Caroline DeMoranville. Compiled and analyzed by the Buzzards Bay NEP.

21 year statistics

For the period October 1, 1988 to October 1, 2009 (21 years), the following statistics were calculated from the UMass Cranberry Experiment Station:
For daily (24 hr) rainfalls, the max daily rainfall was 5.27 inches, the minimum monthly was 0.21 inches (August 1993), the max monthly was 14.78 inches (September 1996), and the max yearly was 64.78, the min yearly was 39.51 inches, and the annual average including trace amounts (presumed =0.005 inches) was 50.66 inches. On average, each year had 229 days with no rain and 136 days with some rain, of which 126 days had measurable rain. Of the days with rain (including trace), 90% of the rainfalls were 1.02 inches or below, and 95% of the rains (with trace events included) are 1.42 inches or below. However, if you consider only rainfalls likely to generate stormwater (typically more than 0.1 inches, or dropping 1/3 of all measurable rain events), then the 95th percentile is 1.72 inches in Wareham. Values for "storms" (i.e. greater than 24 hours of rain) are considerable higher.


Cumulative Rainfall Frequency

The Buzzards Bay NEP is promoting recently promulgated US EPA federal standards for sizing stormwater stormwater treatment systems. The 2009 Section 438 standards (read the Section 438 technical guidance require that stormwater practices retain the 95th percentile storm. The recommended methodology for this calculation is to exclude rainfall events that "are 0.1 of an inch or less" from the "percentile analysis because this rainfall generally does not result in any measureable runoff due to absorption, interception and evaporation by permeable, impermeable and vegetated surfaces." The federal guidance also notes that "at least a 20-30 year period of rainfall record is recommended for such an analysis."

The Buzzards Bay NEP analyzed precipitation data for East Wareham collected by the UMass Cranberry Experiment Station that was available for the past 22 years to calculate the 95th percentile storm. There are 3,000 24-hr rainfall events for this 22-year record, but 232 of these are "trace" measurements, with no numeric value recorded. Including these trace rainfalls in the analysis, the 95th percentile rainfall is 1.40 inches. Excluding these trace events (as is typically done to define storm size storms for regulations), results in a 95th percentile rainfall of 1.45 inches. However, there are 1,020 events for this 22 between trace rainfall and up to and including 0.1 inches (1/3 of all measurable rain events). Discarding these events the 95th percentile is 1.72 inches in Wareham.

22 year rainfall frequency in Wareham, MA

Rainfall percentile storm calculation for East Wareham Cranberry Experiment Station. The western shore of Buzzards Bay has somewhat higher annual precipitation than this station.

Rainfall frequency table and chart as pdf file.


Woods Hole Oceanographic Institution Historical Climate Data (solar rad, temp, precip)

Groundwater and surface Water Data

USGS' Massachusetts Climate Response Network page
Great site, just click on the map to obtain historical average groundwater elevations for long term monitoring well sites.

USGS Surface Water Levels Data retrieval page for Massachusetts

Groundwater Levels: Historic and Recent for two sites

The graphs below for two wells, one in Duxbury (continuous monitoring), and one in Wareham (monthly reporting) will give you a sense as to how recent rainfall may be affecting groundwater in our region. Red Line shows actual levels for this past year (live link from USGS) versus historic levels (colored interval bands and historic monthly means).

USGS groundwater data for Duxbury, MA
more info

USGS groundwater data for Lakeville, MA
more info

USGS groundwater data graph key

Stream Flow

USGS' Water watch page
Click on the map to obtain real time stream monitoring data.

USGS' Paskamanset River, Dartmouth, MA Real Time page