NCDC /
Climate Monitoring /
NA-DM / Stnd Precipitation Index /
Help
North American Drought Monitor
Standardized Precipitation Index
|
Canada is not included in the contour maps because of the limited number of climatological stations currently available. Until sufficient data are made available to increase the station density so that contours can
be more accurately drawn, Canadian data will be provided only on the dot
maps.
 Overview
The Standardized Precipitation Index (SPI) is a probability index that considers only
precipitation. The SPI is an index based on the probability of recording a given amount of precipitation, and the probabilities are standardized so that an index of zero indicates the median precipitation amount (half of the historical precipitation amounts are below the median, and half are above the median). The index is negative for drought, and positive for wet conditions. As the dry or wet conditions become more severe, the index becomes more negative or positive. The SPI is computed by NCDC for several time scales, ranging from one month to 24 months, to capture the various scales of both short-term and long-term drought.
North American 1-Month SPI Dot Map
Click on image above for larger view
US and Mexico 1-Month SPI Contours
Click on image above for larger view
North American 2-Month SPI Dot Map
Click on image above for larger view
US and Mexico 2-Month SPI Contours
Click on image above for larger view
North American 3-Month SPI Dot Map
Click on image above for larger view
US and Mexico 3-Month SPI Contours
Click on image above for larger view
North American 6-Month SPI Dot Map
Click on image above for larger view
US and Mexico 6-Month SPI Contours
Click on image above for larger view
North American 9-Month SPI Dot Map
Click on image above for larger view
US and Mexico 9-Month SPI Contours
Click on image above for larger view
North American 12-Month SPI Dot Map
Click on image above for larger view
US and Mexico 12-Month SPI Contours
Click on image above for larger view
North American 24-Month SPI Dot Map
Click on image above for larger view
US and Mexico 24-Month SPI Contours
Click on image above for larger view
For further information on the data presented here, contact:
David Levinson
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: David.Levinson@noaa.gov
-or-
Richard Heim
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: Richard.Heim@noaa.gov
Top of Page
NCDC /
Climate Monitoring /
NA-DM / Standardized Precipitation Index
/
Help
|
