snotelpy 0.2.2

SNOTEL API Wrapper for the NRCS RESTful API for quick dataset/dataframe building

snotelpy

Snotelpy is a lightweight Python Package interface for accessing USDA SNOTEL station data, allowing researchers to quickly retrieve, filter, and analyze snowpack variables across all SNOTEL stations and watersheds via the NRCS AWDB RESTful API.

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Motivation

I built this package as there is currently no actively maintained, modern Python package built on the newer NRCS AWDB RESTful API. The previous WSDL/SOAP API used to request SNOTEL data is being transitioned away to the newer AWDB RESTful API.

snotelpy fills this gap - giving researchers a simple, Python interface to fetch, filter, and analyze snowpack data from SNOTEL stations without manually constructing API URLs or cleaning raw JSON responses.

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Installation

pip install snotelpy

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Quick Start

import snotelpy as sp 

#Fetch daily SWE and precipitation for two Colorado stations (2020 water year)
ds = sp.fetch_snotel(
    stations=["602:CO:SNTL", "913:CO:SNTL"],
    elements=["WTEQ", "PREC"],
    duration="DAILY",
    start_date="2019-10-01",
    end_date="2020-09-30"
)

# Print resulting xarray Dataset with (time, stations) dimensions
print(ds)

Functions

fetch_snotel(stations, elements, duration, start_date, end_date, include_coords)

Fetches one or more SNOTEL variables across one or more stations and returns an xarray.Dataset with (time, station) dimensions. Automatically chunks large requests that exceed the API's 500,000-point limit.

Parameter	Type	Default	Description
stations	list	required	Station triplets, e.g. ["602:CO:SNTL"]. Supports * wildcard.
elements	list	required	Element codes, e.g. ["WTEQ", "PREC"].
duration	str	"DAILY"	"DAILY", "HOURLY", "SEMIMONTHLY", "MONTHLY", "CALENDAR_YEAR", "WATER_YEAR"
start_date	str	"1991-01-01"	Begin date in YYYY-MM-DD format.
end_date	str	"2100-01-01"	End date in YYYY-MM-DD format.
include_coords	bool	False	If True, attach latitude, longitude, and elevation as dataset coordinates.

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get_stations(station_triplets, elements, hucs, county_name, station_name, returnStationElements, returnType)

Queries the AWDB API for stations matching the given filters and returns a pandas.DataFrame or a geopandas.GeoDataFrame (EPSG:4326).

Parameter	Type	Default	Description
station_triplets	list	["::SNTL"]	All SNOTEL stations by default.
elements	list	[]	Filter by element codes, e.g. ["WTEQ"].
hucs	list	[]	Filter by HUC watershed codes, e.g. ["10"].
county_name	str	""	Filter by county name, e.g. "Boulder".
station_name	str	""	Filter by station name.
returnStationElements	bool	False	If True returns all the possible elements the request stations record.
returnType	str	"pd"	"pd" for pandas DataFrame, "gpd" for GeoDataFrame.

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plot.element_timeseries(ds, element, show_plot, ax, figsize)

Plots a time series for a given SNOTEL element across all stations in a dataset. Returns the matplotlib Axes object for further customization or embedding in subplots.

Parameter	Type	Default	Description
ds	xarray.Dataset	required	Dataset returned by fetch_snotel().
element	str	"WTEQ"	Element code to plot, e.g. "WTEQ", "SNWD", "TAVG".
show_plot	bool	True	If False, suppresses plt.show() for embedding in subplots or saving.
ax	matplotlib.axes.Axes	None	Axes to plot onto. If None, a new figure is created.
figsize	tuple	(10, 4)	Figure size in inches. Only used when ax is None.

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save_data(ds, path)

Saves a dataset returned by fetch_snotel() to disk. Will save a xarray.Dataset as a netcdf, a GeoDataFrame as a GeoJSON and a pandas.Dataframe as a .csv.

Parameter	Type	Default	Description
ds	xarray.Dataset or pandas.Dataframe	required	Dataset to save.
path	str	required	Output file path.

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basin_summary(hucs, elements, duration, start_date, end_date, climatology_period)

Retrieves basin-averaged statistics and monthly climatology for a SNOTEL watershed basin identified by Hydrologic Unit Code (HUC). Returns a dictionary with three keys.

Parameter	Type	Default	Description
hucs	list	required	HUC codes to query, e.g. [1019]. See USGS HUC structure.
elements	list	["WTEQ","PREC","SNWD","TAVG","TMAX","TMIN"]	Element codes to retrieve.
duration	str	"DAILY"	"DAILY" or "MONTHLY".
start_date	str	"1991-01-01"	Begin date in YYYY-MM-DD format.
end_date	str	"2100-01-01"	End date in YYYY-MM-DD format.
climatology_period	tuple	("1991-10-01", "2020-09-30")	Start and end of the climatology window. Must fall within start_date/end_date.

Returns a dict with three keys:

Key	Type	Description
basin_stats	xarray.Dataset	Basin-averaged MEAN, MEDIAN, MAX, MIN across all stations. Dimensions: (stat, time).
climatology	xarray.Dataset	Monthly climatology over the specified period. Dimensions: (climatology, month).
stations	geopandas.GeoDataFrame	All SNOTEL stations within the requested HUC(s), EPSG:4326.

Usage:

out = sp.basin_summary(
    hucs=[1019],
    elements=["WTEQ"],
    duration="MONTHLY",
    start_date="2000-10-01",
    end_date="2025-10-01",
    climatology_period=("2000-10-01", "2025-10-01")
)

basin_stats  = out["basin_stats"]
climatology  = out["climatology"]
stations     = out["stations"]

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Basic usage:

ds = sp.fetch_snotel(
    stations=["602:CO:SNTL", "913:CO:SNTL"],
    elements=["WTEQ"],
    start_date="2022-10-01",
    end_date="2023-03-31"
)
ax = sp.plot.element_timeseries(ds, element="WTEQ")

Embedding in a subplot:

fig, axes = plt.subplots(2, 1, figsize=(10, 8))
sp.plot.element_timeseries(ds, element="WTEQ", show_plot=False, ax=axes[0])
sp.plot.element_timeseries(ds, element="SNWD", show_plot=False, ax=axes[1])
plt.tight_layout()
plt.show()

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Common Element Codes

Code	Description	Units
WTEQ	Snow Water Equivalent	in
PREC	Precipitation Accumulation	in
SNWD	Snow Depth	in
TAVG	Air Temperature Average	°F
TMAX	Air Temperature Maximum	°F
TMIN	Air Temperature Minimum	°F

See ELEMENTS.yaml for all elements supported in the NRCS networks, note -- SNOTEL doesn't support most of these elements.

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Examples

See the Examples notebook for complete workflows including:

• Single-station SWE time series
• Multi-station HUC-filtered requests
• Elevation vs. SWE scatter plots
• GeoDataFrame mapping

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Data Source

Data is sourced from the USDA NRCS Air-Water Database (AWDB) REST API.

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Planned Extensions

• SCAN (Soil Climate Analysis Network) support

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License

MIT License — see LICENSE.txt