Destination Weather API

Weather forecasts, reports on current weather conditions, astronomical information and alerts at a specific location based on the ‘HERE Destination Weather’ API.

Observations

In order to request information about the current weather situation points of interest (POIs) have to be provided. The POIs must be an sf object containing geometries of type POINT or a character vector containing place names (e.g. cities). These POIs are passed to the weather() function, whereby the product parameter is set to "observation":

observation <- weather(
  poi = poi,
  product = "observation"
)

The return value is an sf object, which contains the POINT geometries of the provided POIs and the most recent record on the observed weather. The measurements are taken from the nearest weather observation stations with respect to the POIs. The distance of the stations to the provided POIs is an indicator for the reliabilty of the weather information at each POI. A table of the observed weather near the example POIs:

station distance description temperature humidity windSpeed windDirection
Rönnimoos 450 Passing clouds. Warm. 25.00 54 20.39 20
Lugano 670 Passing clouds. Warm. 30.00 46 7.41 190
Chailly 340 Warm. 27.89 41 14.83 40
Kleinhüningen 430 Sunny. Warm. 26.00 54 24.09 0
Kehrsatz 620 Passing clouds. Warm. 26.00 48 14.83 50
Zürich (Kreis 6) / Oberstrass 820 Passing clouds. Warm. 25.00 54 18.53 80
Geneva 490 Sunny. Pleasantly warm. 28.00 40 22.24 40
Vaduz 940 Mild. 24.72 57 14.83 340

Print the weather observation information on an interactive leaflet map:

m <-
  mapview(observation,
          zcol = "temperature",
          cex = observation$humidity/4,
          layer.name = "Observation",
          map.types = c("Esri.WorldTopoMap"),
          homebutton = FALSE
  ) + 
  mapview(poi,
          zcol = "city",
          cex = 1,
          col.region = "black",
          legend = FALSE,
          homebutton = FALSE
  )
m

Forecast

An hourly forecast of the predicted weather for the following seven days can be obtained by setting the product parameter to "forecast_hourly"

forecast <- weather(
  poi = poi,
  product = "forecast_hourly"
)

Print the weather observation information on an interactive leaflet map with popup graphs for temperature and humidity:

  1. Create a list containing the temperature and humidity graphs for every POI:
g <- lapply(1:nrow(forecast), function(x) {
  fc <- data.frame(
    dt = as.POSIXct(forecast$forecast[[x]]$utcTime, format = "%Y-%m-%dT%H:%M:%OS", tz = "UTC"),
    te = as.numeric(forecast$forecast[[x]]$temperature),
    rh = as.numeric(forecast$forecast[[x]]$humidity)
  )
  ggplot(fc, aes(x = dt)) + 
    geom_line(aes(y = te, colour = "Temperature")) +
    geom_line(aes(y = rh/5, colour = "Humidity")) +
    scale_y_continuous(sec.axis = sec_axis(~.*5, name = "Relative humidity [%]")) + 
    scale_colour_manual(values = c("blue", "red")) +
    labs(y = "Air temperature [°C]", x = "", colour = "") +
    ggtitle(forecast$station[x]) +
    theme_minimal() +
    theme(legend.position="bottom", panel.background = element_rect(color = NA))
})
  1. Then add list of graphs to the leaflet map using the the popup parameter:
m <-
  mapview(forecast,
          color = "black",
          col.region = "yellow",
          layer.name = "Forecast",
          zcol = "station",
          map.types = c("Esri.WorldTopoMap"),
          homebutton = FALSE,
          legend = FALSE,
          popup = leafpop::popupGraph(g)
  ) + 
  mapview(poi,
          zcol = "city",
          cex = 1,
          col.region = "black",
          legend = FALSE,
          homebutton = FALSE
  )
m

Astronomy

An astronomical forecast is requested by setting the product parameter to "forecast_astronomy":

astronomy <- weather(
  poi = poi,
  product = "forecast_astronomy"
)
Print a table for the sun and moon times of the first example POI, where the nearest station is ‘Emmenbrücke’:
date sunrise sunset moonrise moonset phase
2020-09-17 7:07AM 7:33PM 6:41AM 8:04PM New moon
2020-09-18 7:09AM 7:31PM 8:03AM 8:29PM New moon
2020-09-19 7:10AM 7:29PM 9:26AM 8:54PM Waxing crescent
2020-09-20 7:11AM 7:27PM 10:48AM 9:21PM Waxing crescent
2020-09-21 7:11AM 7:27PM 10:48AM 9:21PM Waxing crescent
2020-09-22 7:14AM 7:23PM 1:28PM 10:30PM Waxing crescent
2020-09-23 7:15AM 7:21PM 2:41PM 11:15PM Waxing crescent
2020-09-24 7:17AM 7:19PM 3:45PM
First Quarter

Alerts

Current weather alerts, near provided POIs, are obtain by the product alerts:

alerts <- weather(
  poi = poi,
  product = "alerts"
)

This returns an sf object with the POIs and the attribute "alerts", which is a data.table, which contains the current weather alerts. If no alerts are recorded near a POI the attribute "alerts" is NULL.

API Reference