brozek/website
1
0
Fork 0
mirror of https://github.com/Brandon-Rozek/website.git synced 2025-08-03 23:31:59 +00:00
Code Issues Projects Releases Packages Activity

New post

Browse source
This commit is contained in:
Brandon Rozek 2025-03-16 16:19:33 -04:00
parent 83962f82db
commit 7f268b8219
1 changed files with 556 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

556
content/blog/weather-forcecasts-cli-nws.md Normal file
View file

@ -0,0 +1,556 @@
---
title: "Weather Forcecasts on the Command-Line with the National Weather Service API"
date: 2025-03-16T15:33:49-04:00
draft: true
tags: []
math: false
medium_enabled: false
---
The United States National Weather Service (NWS) has a [JSON API](https://www.weather.gov/documentation/services-web-api) which provides weather alerts and forecasts for free without having to create an API key[^1]. We'll use this resource to write a small bash script which gives today and tomorrow's weather forecast given a latitude and longitude.
[^1]: In this day and age, it almost feels too good to be true.
My goal is to have a small bash script which I can run in the terminal to get the forecast information. We'll use [`jq`](https://jqlang.org/) for handling the JSON data.
The NWS API does not provide the forecast directly given a latitude and longitude coordinates. Instead, we need to provide the specific [Weather Forecast Office (WFO)](https://www.weather.gov/srh/nwsoffices) responsible for that area plus their grid definitions for the latitude and longitude coordinate.
Luckily, we can query for that information as well.
```bash
POINTS=$(curl -Ls "https://api.weather.gov/points/$LAT,$LON")
```
{{< unsafe >}}<details><summary>For 42.7289, -73.6915 it returns:</summary>{{</unsafe >}}
```json
{
"@context": [
"https://geojson.org/geojson-ld/geojson-context.jsonld",
{
"@version": "1.1",
"wx": "https://api.weather.gov/ontology#",
"s": "https://schema.org/",
"geo": "http://www.opengis.net/ont/geosparql#",
"unit": "http://codes.wmo.int/common/unit/",
"@vocab": "https://api.weather.gov/ontology#",
"geometry": {
"@id": "s:GeoCoordinates",
"@type": "geo:wktLiteral"
},
"city": "s:addressLocality",
"state": "s:addressRegion",
"distance": {
"@id": "s:Distance",
"@type": "s:QuantitativeValue"
},
"bearing": {
"@type": "s:QuantitativeValue"
},
"value": {
"@id": "s:value"
},
"unitCode": {
"@id": "s:unitCode",
"@type": "@id"
},
"forecastOffice": {
"@type": "@id"
},
"forecastGridData": {
"@type": "@id"
},
"publicZone": {
"@type": "@id"
},
"county": {
"@type": "@id"
}
}
],
"id": "https://api.weather.gov/points/42.7289,-73.6915",
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
-73.6915,
42.7289
]
},
"properties": {
"@id": "https://api.weather.gov/points/42.7289,-73.6915",
"@type": "wx:Point",
"cwa": "ALY",
"forecastOffice": "https://api.weather.gov/offices/ALY",
"gridId": "ALY",
"gridX": 74,
"gridY": 67,
"forecast": "https://api.weather.gov/gridpoints/ALY/74,67/forecast",
"forecastHourly": "https://api.weather.gov/gridpoints/ALY/74,67/forecast/hourly",
"forecastGridData": "https://api.weather.gov/gridpoints/ALY/74,67",
"observationStations": "https://api.weather.gov/gridpoints/ALY/74,67/stations",
"relativeLocation": {
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
-73.707011,
42.724883
]
},
"properties": {
"city": "Watervliet",
"state": "NY",
"distance": {
"unitCode": "wmoUnit:m",
"value": 1343.4228258697
},
"bearing": {
"unitCode": "wmoUnit:degree_(angle)",
"value": 70
}
}
},
"forecastZone": "https://api.weather.gov/zones/forecast/NYZ053",
"county": "https://api.weather.gov/zones/county/NYC083",
"fireWeatherZone": "https://api.weather.gov/zones/fire/NYZ208",
"timeZone": "America/New_York",
"radarStation": "KENX"
}
}
```
{{< unsafe >}}</details><br/>{{</unsafe >}}
That's a lot of output! However, we only need three pieces of information:
- WFO office (ex: "ALY")
- Grid-X (ex: 74)
- Grid-Y (ex: 67)
We can use the following code to store this into variables using `jq`
```bash
OFFICE=$(echo $POINTS | jq -r .properties.gridId)
X=$(echo $POINTS | jq .properties.gridX)
Y=$(echo $POINTS | jq .properties.gridY)
```
From here, we can query for the weather forecast for that grid point.
```bash
WEATHER=$(curl -Ls "https://api.weather.gov/gridpoints/$OFFICE/$X,$Y/forecast")
```
{{< unsafe >}}<details><summary>Show output:</summary>{{</unsafe >}}
```json
{
"@context": [
"https://geojson.org/geojson-ld/geojson-context.jsonld",
{
"@version": "1.1",
"wx": "https://api.weather.gov/ontology#",
"geo": "http://www.opengis.net/ont/geosparql#",
"unit": "http://codes.wmo.int/common/unit/",
"@vocab": "https://api.weather.gov/ontology#"
}
],
"type": "Feature",
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-73.6648,
42.7172
],
[
-73.6602,
42.7386
],
[
-73.6893,
42.742
],
[
-73.694,
42.720499999999994
],
[
-73.6648,
42.7172
]
]
]
},
"properties": {
"units": "us",
"forecastGenerator": "BaselineForecastGenerator",
"generatedAt": "2025-03-16T19:59:48+00:00",
"updateTime": "2025-03-16T19:38:29+00:00",
"validTimes": "2025-03-16T13:00:00+00:00/P8D",
"elevation": {
"unitCode": "wmoUnit:m",
"value": 61.8744
},
"periods": [
{
"number": 1,
"name": "This Afternoon",
"startTime": "2025-03-16T15:00:00-04:00",
"endTime": "2025-03-16T18:00:00-04:00",
"isDaytime": true,
"temperature": 69,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "22 mph",
"windDirection": "S",
"icon": "https://api.weather.gov/icons/land/day/wind_ovc?size=medium",
"shortForecast": "Cloudy",
"detailedForecast": "Cloudy, with a high near 69. South wind around 22 mph, with gusts as high as 43 mph. New rainfall amounts less than a tenth of an inch possible."
},
{
"number": 2,
"name": "Tonight",
"startTime": "2025-03-16T18:00:00-04:00",
"endTime": "2025-03-17T06:00:00-04:00",
"isDaytime": false,
"temperature": 50,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 100
},
"windSpeed": "5 to 21 mph",
"windDirection": "SW",
"icon": "https://api.weather.gov/icons/land/night/tsra,100?size=medium",
"shortForecast": "Showers And Thunderstorms",
"detailedForecast": "A chance of rain showers before 8pm, then showers and thunderstorms. Cloudy, with a low around 50. Southwest wind 5 to 21 mph, with gusts as high as 44 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible."
},
{
"number": 3,
"name": "Monday",
"startTime": "2025-03-17T06:00:00-04:00",
"endTime": "2025-03-17T18:00:00-04:00",
"isDaytime": true,
"temperature": 53,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 60
},
"windSpeed": "5 to 12 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/day/rain_showers,60/rain_showers,50?size=medium",
"shortForecast": "Rain Showers Likely",
"detailedForecast": "Rain showers likely. Cloudy. High near 53, with temperatures falling to around 46 in the afternoon. Northwest wind 5 to 12 mph. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible."
},
{
"number": 4,
"name": "Monday Night",
"startTime": "2025-03-17T18:00:00-04:00",
"endTime": "2025-03-18T06:00:00-04:00",
"isDaytime": false,
"temperature": 31,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 30
},
"windSpeed": "7 to 10 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/night/rain_showers,30/bkn?size=medium",
"shortForecast": "Chance Rain Showers then Mostly Cloudy",
"detailedForecast": "A chance of rain showers before 8pm. Mostly cloudy, with a low around 31. Northwest wind 7 to 10 mph. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch possible."
},
{
"number": 5,
"name": "Tuesday",
"startTime": "2025-03-18T06:00:00-04:00",
"endTime": "2025-03-18T18:00:00-04:00",
"isDaytime": true,
"temperature": 56,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "7 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/day/few?size=medium",
"shortForecast": "Sunny",
"detailedForecast": "Sunny, with a high near 56. Northwest wind around 7 mph."
},
{
"number": 6,
"name": "Tuesday Night",
"startTime": "2025-03-18T18:00:00-04:00",
"endTime": "2025-03-19T06:00:00-04:00",
"isDaytime": false,
"temperature": 35,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "1 to 5 mph",
"windDirection": "NE",
"icon": "https://api.weather.gov/icons/land/night/few?size=medium",
"shortForecast": "Mostly Clear",
"detailedForecast": "Mostly clear, with a low around 35."
},
{
"number": 7,
"name": "Wednesday",
"startTime": "2025-03-19T06:00:00-04:00",
"endTime": "2025-03-19T18:00:00-04:00",
"isDaytime": true,
"temperature": 65,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "2 to 9 mph",
"windDirection": "SE",
"icon": "https://api.weather.gov/icons/land/day/sct?size=medium",
"shortForecast": "Mostly Sunny",
"detailedForecast": "Mostly sunny, with a high near 65."
},
{
"number": 8,
"name": "Wednesday Night",
"startTime": "2025-03-19T18:00:00-04:00",
"endTime": "2025-03-20T06:00:00-04:00",
"isDaytime": false,
"temperature": 45,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "9 mph",
"windDirection": "SE",
"icon": "https://api.weather.gov/icons/land/night/bkn?size=medium",
"shortForecast": "Mostly Cloudy",
"detailedForecast": "Mostly cloudy, with a low around 45."
},
{
"number": 9,
"name": "Thursday",
"startTime": "2025-03-20T06:00:00-04:00",
"endTime": "2025-03-20T18:00:00-04:00",
"isDaytime": true,
"temperature": 61,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 50
},
"windSpeed": "8 to 14 mph",
"windDirection": "S",
"icon": "https://api.weather.gov/icons/land/day/bkn/rain_showers,50?size=medium",
"shortForecast": "Mostly Cloudy then Chance Rain Showers",
"detailedForecast": "A chance of rain showers after 2pm. Mostly cloudy, with a high near 61. Chance of precipitation is 50%."
},
{
"number": 10,
"name": "Thursday Night",
"startTime": "2025-03-20T18:00:00-04:00",
"endTime": "2025-03-21T06:00:00-04:00",
"isDaytime": false,
"temperature": 33,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 70
},
"windSpeed": "8 to 12 mph",
"windDirection": "SW",
"icon": "https://api.weather.gov/icons/land/night/rain_showers,70/snow,70?size=medium",
"shortForecast": "Rain Showers Likely then Chance Rain And Snow Showers",
"detailedForecast": "Rain showers likely before 2am, then a chance of rain and snow showers. Mostly cloudy, with a low around 33. Chance of precipitation is 70%."
},
{
"number": 11,
"name": "Friday",
"startTime": "2025-03-21T06:00:00-04:00",
"endTime": "2025-03-21T18:00:00-04:00",
"isDaytime": true,
"temperature": 41,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": 50
},
"windSpeed": "12 to 17 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/day/snow,50/snow,30?size=medium",
"shortForecast": "Chance Rain And Snow Showers",
"detailedForecast": "A chance of rain and snow showers. Partly sunny, with a high near 41. Chance of precipitation is 50%."
},
{
"number": 12,
"name": "Friday Night",
"startTime": "2025-03-21T18:00:00-04:00",
"endTime": "2025-03-22T06:00:00-04:00",
"isDaytime": false,
"temperature": 30,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "9 to 16 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/night/snow/sct?size=medium",
"shortForecast": "Slight Chance Snow Showers then Partly Cloudy",
"detailedForecast": "A slight chance of snow showers before 8pm. Partly cloudy, with a low around 30."
},
{
"number": 13,
"name": "Saturday",
"startTime": "2025-03-22T06:00:00-04:00",
"endTime": "2025-03-22T18:00:00-04:00",
"isDaytime": true,
"temperature": 52,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "9 to 13 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/day/sct?size=medium",
"shortForecast": "Mostly Sunny",
"detailedForecast": "Mostly sunny, with a high near 52."
},
{
"number": 14,
"name": "Saturday Night",
"startTime": "2025-03-22T18:00:00-04:00",
"endTime": "2025-03-23T06:00:00-04:00",
"isDaytime": false,
"temperature": 34,
"temperatureUnit": "F",
"temperatureTrend": "",
"probabilityOfPrecipitation": {
"unitCode": "wmoUnit:percent",
"value": null
},
"windSpeed": "3 to 9 mph",
"windDirection": "NW",
"icon": "https://api.weather.gov/icons/land/night/bkn?size=medium",
"shortForecast": "Mostly Cloudy",
"detailedForecast": "Mostly cloudy, with a low around 34."
}
]
}
}
```
{{< unsafe >}}</details><br/>{{</unsafe >}}
The National Weather Service packs in so much weather information in just one API call! My favorite part is that they have a `detailedForecast` field which provides a nice human-readable description of the weather.
I don't know about you, but at any given time, I'm mostly curious about today and tomorrow's weather. Unless I'm planning a trip or need to be aware of an extreme weather event, the day's forecast mostly influences the clothes I wear.
The final part of this script is to grab the next three "periods" and display its `detailedForecast` field.
```bash
for i in 0 1 2; do
echo "$WEATHER" | jq .properties.periods[$i] | jq -r '
"\(.name)
\(.detailedForecast)
"
'
done
```
Instead of having to read an entire JSON message to get the weather, we now have a description of the forecast coming up.
```
This Afternoon
Cloudy, with a high near 69. South wind around 22 mph, with gusts as high as 43 mph. New rainfall amounts less than a tenth of an inch possible.
Tonight
A chance of rain showers before 8pm, then showers and thunderstorms. Cloudy, with a low around 50. Southwest wind 5 to 21 mph, with gusts as high as 44 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible.
Monday
Rain showers likely. Cloudy. High near 53, with temperatures falling to around 46 in the afternoon. Northwest wind 5 to 12 mph. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.
```
Look how short and sweet that output is! With that, we have all the steps needed in our script to grab the upcoming forecast using the NWS API. I created an alias called `myweather` so that I don't have to memorize the latitude or longitude of where I live.
```bash
alias myweather='usweather 42.7289, -73.6915'
```
Here is the script that I call `usweather` in its entirety. I placed it in `~/.local/bin`.
```bash
#!/bin/sh
# Script to query the US National Weather Forecast Office (WFO)
set -o errexit
set -o nounset
show_usage() {
echo "Usage: usweather [lat] [lon]"
exit 1
}
# Check Argument Count
if [ "$#" -ne 2 ]; then
show_usage
fi
if ! command -v jq &> /dev/null; then
echo "jq is not installed"
exit 1
fi
# We need to figure out WFO specific parameters
POINTS=$(curl -Ls "https://api.weather.gov/points/$1,$2")
OFFICE=$(echo $POINTS | jq -r .properties.gridId)
X=$(echo $POINTS | jq .properties.gridX)
Y=$(echo $POINTS | jq .properties.gridY)
if [ "$OFFICE" = "null" ] || [ "$X" = "null" ] || [ "$Y" = "null" ]; then
echo -e "Error:\n $POINTS"
exit 1
fi
WEATHER=$(curl -Ls "https://api.weather.gov/gridpoints/$OFFICE/$X,$Y/forecast")
# Provide the detailed forecast for the next three weather periods
for i in 0 1 2; do
echo "$WEATHER" | jq .properties.periods[$i] | jq -r '
"\(.name)
\(.detailedForecast)
"
'
done
```