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 Sprinkles. Broken clouds. Quite cool. 7.00 71 18.53 240
Lugano 670 Sunny. Cool. 12.00 38 27.80 10
Chailly 340 Quite cool. 6.61 81 9.27 280
Kleinhüningen 430 Partly sunny. Cool. 8.00 76 16.68 260
Kehrsatz 620 Light rain. Broken clouds. Quite cool. 6.00 76 9.27 250
Zürich (Kreis 6) / Oberstrass 820 Sprinkles. Broken clouds. Quite cool. 5.00 87 5.56 310
Geneva 490 Broken clouds. Quite cool. 7.00 81 24.09 210
Vaduz 940 Chilly. 2.28 91 1.85 280

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
2020-01-29 7:56AM 5:24PM 10:21AM 10:04PM Waxing crescent
2020-01-30 7:55AM 5:25PM 10:41AM 11:06PM Waxing crescent
2020-01-31 7:54AM 5:27PM 11:01AM
Waxing crescent
2020-02-01 7:52AM 5:29PM 11:22AM 12:09AM Waxing crescent
2020-02-02 7:51AM 5:30PM 11:45AM 1:12AM First Quarter
2020-02-03 7:50AM 5:32PM 12:12PM 2:17AM First Quarter
2020-02-04 7:48AM 5:33PM 12:45PM 3:24AM Waxing gibbous
2020-02-05 7:47AM 5:35PM 1:27PM 4:31AM Waxing gibbous

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