This repository is an archive of weekly US Drought Monitor (USDM) data aggregated to the county level as reported by the USDM.
📂 View the US Drought Monitor county aggregation archive listing here.
The county data archived in this repository were acquired via API request by R. Kyle Bocinsky (Montana Climate Office) and are updated weekly. API documentation is available at https://droughtmonitor.unl.edu/DmData/DataDownload/WebServiceInfo.aspx.
Here is a template of the call used to retrieve these data:
https://usdmdataservices.unl.edu/api/CountyStatistics/GetDroughtSeverityStatisticsByAreaPercent?aoi=AK,AL,AR,AZ,CA,CO,CT,DC,DE,FL,GA,HI,IA,ID,IL,IN,KS,KY,LA,MA,MD,ME,MI,MN,MO,MS,MT,NC,ND,NE,NH,NJ,NM,NV,NY,OH,OK,OR,PA,PR,RI,SC,SD,TN,TX,UT,VA,VT,WA,WI,WV,WY&startdate=01/04/2000&enddate=01/04/2000&statisticsType=2
📈 About the US Drought Monitor (USDM)
The US Drought Monitor is a weekly map-based product that synthesizes multiple drought indicators into a single national assessment. It is produced by:
- National Drought Mitigation Center (NDMC)
- US Department of Agriculture (USDA)
- National Oceanic and Atmospheric Administration (NOAA)
Each weekly map represents a combination of data analysis and expert interpretation.
The USDM weekly maps depicting drought conditions are categorized into six levels:
- None: Normal or wet conditions
- D0: Abnormally Dry
- D1: Moderate Drought
- D2: Severe Drought
- D3: Extreme Drought
- D4: Exceptional Drought
While USDM drought class boundaries are developed without regard to political boundaries, it is often aggregated by political boundaries to assist in decision-making and for regulatory purposes.
Note: This archive is maintained by the Montana Climate Office, but all analytical authorship of the USDM drought maps belongs to the named USDM authors.
🗂 Directory Structure
<usdm-counties-reported.R>: R script that downloads weekly USDM data aggregated to county boundaries.<usdm-counties-reported.parquet>: Processed county-level USDM data in a single parquet file.<data/>: Directory containing processed county-level USDM data.<README.Rmd>: This README file, providing an overview and usage instructions.
📍 Quick Start: Visualize a Weekly County USDM Map in R
This snippet shows how to load a weekly GeoParquet file from the archive
and create a simple drought classification map using sf and ggplot2.
# Load required libraries
library(arrow)
library(sf)
library(ggplot2) # For plotting
library(tigris) # For state boundaries
library(rmapshaper) # For innerlines function
## Get latest USDM data
latest <-
jsonlite::fromJSON(
"manifest.json"
)$path |>
stringr::str_subset("parquet") |>
stringr::str_subset("data/usdm") |>
max()
# e.g., [1] "data/usdm/USDM_2025-05-27.parquet"
date <-
latest |>
stringr::str_extract("\\d{4}-\\d{2}-\\d{2}") |>
lubridate::as_date()
# Get the highest (worst) drought class in each county
usdm <-
latest |>
arrow::read_parquet() |>
dplyr::group_by(STATEFP, COUNTYFP) |>
dplyr::filter(usdm_class == max(usdm_class))
## Load the US Census county data
counties <-
tigris::counties(cb = TRUE,
year = 2020,
resolution = "5m") |>
dplyr::filter(!(STATEFP %in% c("60", "66", "69", "78"))) |>
# transform to WGS 84
sf::st_transform("EPSG:4326") |>
sf::st_cast("POLYGON", warn = FALSE, do_split = TRUE) |>
tigris::shift_geometry() |>
dplyr::group_by(STATEFP, COUNTYFP) |>
dplyr::summarise(.groups = "drop") |>
sf::st_cast("MULTIPOLYGON")
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usdm_counties <-
usdm |>
dplyr::left_join(counties) |>
sf::st_as_sf()
# Plot the map
ggplot(counties) +
geom_sf(data = sf::st_union(counties),
fill = "grey80",
color = NA) +
geom_sf(data = usdm_counties,
aes(fill = usdm_class),
color = NA) +
geom_sf(data = rmapshaper::ms_innerlines(counties),
fill = NA,
color = "white",
linewidth = 0.1) +
geom_sf(data = counties |>
dplyr::group_by(STATEFP) |>
dplyr::summarise() |>
rmapshaper::ms_innerlines(),
fill = NA,
color = "white",
linewidth = 0.2) +
scale_fill_manual(
values = c("grey80",
"#ffff00",
"#fcd37f",
"#ffaa00",
"#e60000",
"#730000"),
drop = FALSE,
name = "Drought\nClass") +
labs(title = "US Drought Monitor",
subtitle = format(date, " %B %d, %Y")) +
theme_void()
📝 Citation & Attribution
Citation format (suggested):
US Drought Monitor authors and R. Kyle Bocinsky YYYY. Archive of US Drought Monitor Weekly Maps Aggregated to County Boundaries as Reported by the US Drought Monitor. Data processed, curated, and archived by R. Kyle Bocinsky, Montana Climate Office. Accessed via GitHub archive, YYYY-MM-DD. https://sustainable-fsa.com/usdm-counties-fsa-lfp/
Acknowledgments:
- Map content and data processing by USDM authors.
- Data curation and archival structure by R. Kyle Bocinsky, Montana Climate Office, University of Montana.
📄 License
- Raw USDM data (NDMC): Public Domain (17 USC § 105)
- Processed data & scripts: © R. Kyle Bocinsky, released under CC0 and MIT License as applicable
⚠️ Disclaimer
This dataset is archived for research and educational use only. The National Drought Mitigation Center hosts the US Drought Monitor. Please visit https://droughtmonitor.unl.edu.
👏 Acknowledgment
This project is part of:
Enhancing Sustainable Disaster Relief in FSA
Programs
Supported by USDA OCE/OEEP and USDA Climate Hubs
Prepared by the Montana Climate Office
📬 Contact
R. Kyle Bocinsky
Director of Climate Extension
Montana Climate Office
📧 kyle.bocinsky@umontana.edu
🌐 https://climate.umt.edu