diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,8 +1,22 @@
+0.3.0
+=====
+
+  * Switch from HTTP to HTTPS API (https://api.openweathermap.org/data/2.5).
+  * Command line utility prints absolute humidity and local time.
+  * Require Servant >= 0.19.
+
+
 0.2.0
 =====
 
   * (* BREAKING *) Made Location a part of the API to
     reduce code duplication.
+
+  * (* BREAKING *) Made all query parameters required.
+
+  * Changed -c to -q for the command line utility.
+
+  * Added forecast weather API.
 
 
 0.1.0
diff --git a/cmd/Print.hs b/cmd/Print.hs
--- a/cmd/Print.hs
+++ b/cmd/Print.hs
@@ -6,7 +6,9 @@
 import Data.List (intercalate)
 import Data.Time.Clock.POSIX (posixSecondsToUTCTime)
 import Data.Time.LocalTime (TimeZone, minutesToTimeZone, utcToZonedTime)
+import Text.Printf (printf)
 
+import Web.OpenWeatherMap.Formulas (absoluteHumidity)
 import qualified Web.OpenWeatherMap.Types.City as City
 import qualified Web.OpenWeatherMap.Types.Coord as Coord
 import qualified Web.OpenWeatherMap.Types.CurrentWeather as CW
@@ -21,16 +23,21 @@
 printCurrectWeather cw =
   putStrLn
     (place ++
+     ", " ++
+     time ++
      ": " ++
      intercalate
        ",  "
        [ w
        , showHumidity mainw
+       , showAbsoluteHumidity mainw
        , showPressure mainw
        , showTemp mainw
        , showWind wind
        ])
   where
+    tz = secondsToTimeZone (CW.timezone cw)
+    time = showLocalTime tz (CW.dt cw)
     w = showWeather $ CW.weather cw
     place = showLocation (CW.name cw) (Sys.country . CW.sys $ cw) (CW.coord cw)
     mainw = CW.main cw
@@ -39,28 +46,34 @@
 printForecastWeather :: FW.ForecastWeather -> IO ()
 printForecastWeather fw = do
   let c = FW.city fw
-      tz = minutesToTimeZone (City.timezone c `div` 60)
+      tz = secondsToTimeZone (City.timezone c)
       place = showLocation (City.name c) (City.country c) (City.coord c)
   putStrLn place
   mapM_ putStrLn (showForecast tz <$> FW.list fw)
 
+secondsToTimeZone :: Int -> TimeZone
+secondsToTimeZone s = minutesToTimeZone (s `div` 60)
+
 showForecast :: TimeZone -> FC.Forecast -> String
 showForecast tz fc =
-  localtime ++
+  showLocalTime tz (FC.dt fc) ++
   ": " ++
   intercalate
     ", "
     [ showWeather (FC.weather fc)
     , showHumidity mainw
+    , showAbsoluteHumidity mainw
     , showPressure mainw
     , showTemp mainw
     , showWind (FC.wind fc)
     ]
   where
-    localtime =
-      show . utcToZonedTime tz . posixSecondsToUTCTime . fromIntegral $ FC.dt fc
     mainw = FC.main fc
 
+showLocalTime :: TimeZone -> Int -> String
+showLocalTime tz =
+  show . utcToZonedTime tz . posixSecondsToUTCTime . fromIntegral
+
 showLocation :: String -> Maybe String -> Coord.Coord -> String
 showLocation name country coord =
   name' ++ maybe "" ("," ++) country ++ " " ++ coords
@@ -78,13 +91,19 @@
   "°, " ++ maybe "?" show (Coord.lon coord) ++ "°)"
 
 showWeather :: [Weather.Weather] -> String
-showWeather w = intercalate "," $ Weather.main <$> w
+showWeather w = intercalate "/" $ Weather.main <$> w
 
 showHumidity :: Main.Main -> String
 showHumidity m = "H " ++ show hm ++ " %"
   where
     hm :: Int
     hm = round . Main.humidity $ m
+
+showAbsoluteHumidity :: Main.Main -> String
+showAbsoluteHumidity m = "ρ " ++ rho ++ " g/m³"
+  where
+    r = absoluteHumidity m
+    rho = maybe "??" (printf "%0.2f") r
 
 -- https://en.wikipedia.org/wiki/Millimeter_of_mercury
 showPressure :: Main.Main -> String
diff --git a/lib/Web/OpenWeatherMap/Client.hs b/lib/Web/OpenWeatherMap/Client.hs
--- a/lib/Web/OpenWeatherMap/Client.hs
+++ b/lib/Web/OpenWeatherMap/Client.hs
@@ -6,12 +6,12 @@
   , getForecast
   ) where
 
-import Network.HTTP.Client (defaultManagerSettings, newManager)
+import Network.HTTP.Client.TLS (newTlsManager)
 import Servant.Client
   ( BaseUrl(BaseUrl)
   , ClientEnv
   , ClientError
-  , Scheme(Http)
+  , Scheme(Https)
   , mkClientEnv
   , runClientM
   )
@@ -40,10 +40,8 @@
 
 defaultEnv :: IO ClientEnv
 defaultEnv = do
-  manager <- newManager defaultManagerSettings
+  manager <- newTlsManager
   return $ mkClientEnv manager baseUrl
 
--- XXX openweathermap.org does not support HTTPS,
--- XXX appid is passed in clear text. Oops.
 baseUrl :: BaseUrl
-baseUrl = BaseUrl Http "api.openweathermap.org" 80 "/data/2.5"
+baseUrl = BaseUrl Https "api.openweathermap.org" 443 "/data/2.5"
diff --git a/lib/Web/OpenWeatherMap/Formulas.hs b/lib/Web/OpenWeatherMap/Formulas.hs
new file mode 100644
--- /dev/null
+++ b/lib/Web/OpenWeatherMap/Formulas.hs
@@ -0,0 +1,37 @@
+{-# LANGUAGE NamedFieldPuns #-}
+
+module Web.OpenWeatherMap.Formulas
+  ( absoluteHumidity
+  ) where
+
+import Web.OpenWeatherMap.Types.Main
+
+{-- | Calculate absolute humidity (g/m³)
+
+Returns 'Nothing' if the temperature is out of range (−30°C,  +35°C).
+
+-}
+absoluteHumidity :: Main -> Maybe Double
+absoluteHumidity Main {temp, humidity}
+  | tC > -30 && tC < 35 = Just $ ahBolton1980 temp humidity
+  | otherwise = Nothing
+  where
+    tC = k2c temp
+
+{-- | Calculate absolute humidity (g/m³)
+
+Ref.: Bolton D. "The Computation of Equivalent Potential Temperature",
+Monthly Weather Review, 1980, 108(7):1046–1053.
+
+-}
+ahBolton1980 ::
+     Double -- ^ Temperature in Kelvins
+  -> Double -- ^ Relative humidity in %
+  -> Double
+ahBolton1980 temp humidity =
+  13.25 * humidity * exp (17.67 * tC / (tC + 243.5)) / temp
+  where
+    tC = k2c temp
+
+k2c :: Double -> Double
+k2c t = t - 273.15
diff --git a/lib/Web/OpenWeatherMap/Types/City.hs b/lib/Web/OpenWeatherMap/Types/City.hs
--- a/lib/Web/OpenWeatherMap/Types/City.hs
+++ b/lib/Web/OpenWeatherMap/Types/City.hs
@@ -11,11 +11,13 @@
 
 import Web.OpenWeatherMap.Types.Coord (Coord)
 
-data City = City
-  { name :: String
-  , country :: Maybe String
-  , coord :: Coord
-  , timezone :: Int
-  , sunset :: Int
-  , sunrise :: Int
-  } deriving (Show, Generic, FromJSON)
+data City =
+  City
+    { name :: String
+    , country :: Maybe String
+    , coord :: Coord
+    , timezone :: Int
+    , sunset :: Int
+    , sunrise :: Int
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Clouds.hs b/lib/Web/OpenWeatherMap/Types/Clouds.hs
--- a/lib/Web/OpenWeatherMap/Types/Clouds.hs
+++ b/lib/Web/OpenWeatherMap/Types/Clouds.hs
@@ -9,6 +9,8 @@
 
 import Data.Aeson (FromJSON)
 
-data Clouds = Clouds
-  { all :: Double
-  } deriving (Show, Generic, FromJSON)
+data Clouds =
+  Clouds
+    { all :: Double
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Coord.hs b/lib/Web/OpenWeatherMap/Types/Coord.hs
--- a/lib/Web/OpenWeatherMap/Types/Coord.hs
+++ b/lib/Web/OpenWeatherMap/Types/Coord.hs
@@ -9,7 +9,9 @@
 
 import Data.Aeson (FromJSON)
 
-data Coord = Coord
-  { lon :: Maybe Double
-  , lat :: Maybe Double
-  } deriving (Show, Generic, FromJSON)
+data Coord =
+  Coord
+    { lon :: Maybe Double
+    , lat :: Maybe Double
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs b/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
--- a/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
+++ b/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
@@ -19,16 +19,19 @@
 
 -- | Response to requests for current weather.
 -- Refer to <https://openweathermap.org/current>.
-data CurrentWeather = CurrentWeather
-  { coord :: Coord
-  , weather :: [Weather]
-  , base :: String
-  , main :: Main
-  , wind :: Wind
-  , clouds :: Clouds
-  , dt :: Int
-  , sys :: Sys
-  , id :: Int
-  , name :: String
-  , cod :: Int
-  } deriving (Show, Generic, FromJSON)
+data CurrentWeather =
+  CurrentWeather
+    { coord :: Coord
+    , weather :: [Weather]
+    , base :: String
+    , main :: Main
+    , wind :: Wind
+    , clouds :: Clouds
+    , dt :: Int
+    , sys :: Sys
+    , timezone :: Int
+    , id :: Int
+    , name :: String
+    , cod :: Int
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Forecast.hs b/lib/Web/OpenWeatherMap/Types/Forecast.hs
--- a/lib/Web/OpenWeatherMap/Types/Forecast.hs
+++ b/lib/Web/OpenWeatherMap/Types/Forecast.hs
@@ -14,10 +14,12 @@
 import Web.OpenWeatherMap.Types.Weather (Weather)
 import Web.OpenWeatherMap.Types.Wind (Wind)
 
-data Forecast = Forecast
-  { dt :: Int
-  , clouds :: Clouds
-  , main :: Main
-  , weather :: [Weather]
-  , wind :: Wind
-  } deriving (Show, Generic, FromJSON)
+data Forecast =
+  Forecast
+    { dt :: Int
+    , clouds :: Clouds
+    , main :: Main
+    , weather :: [Weather]
+    , wind :: Wind
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/ForecastWeather.hs b/lib/Web/OpenWeatherMap/Types/ForecastWeather.hs
--- a/lib/Web/OpenWeatherMap/Types/ForecastWeather.hs
+++ b/lib/Web/OpenWeatherMap/Types/ForecastWeather.hs
@@ -14,7 +14,9 @@
 
 -- | Response to requests for forecast weather.
 -- Refer to <https://openweathermap.org/forecast5>.
-data ForecastWeather = ForecastWeather
-  { list :: [Forecast]
-  , city :: City
-  } deriving (Show, Generic, FromJSON)
+data ForecastWeather =
+  ForecastWeather
+    { list :: [Forecast]
+    , city :: City
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Location.hs b/lib/Web/OpenWeatherMap/Types/Location.hs
--- a/lib/Web/OpenWeatherMap/Types/Location.hs
+++ b/lib/Web/OpenWeatherMap/Types/Location.hs
@@ -10,25 +10,26 @@
   ) where
 
 import Data.Proxy (Proxy(..))
-
+import Data.Text (Text)
+import Data.Text.Encoding (encodeUtf8)
 import Servant.API ((:>))
 import Servant.Client (Client, HasClient, clientWithRoute, hoistClientMonad)
-import Servant.Client.Core.Request (appendToQueryString)
-import Web.HttpApiData (toQueryParam)
+import Servant.Client.Core.Request (Request, appendToQueryString)
+import Web.HttpApiData (ToHttpApiData, toQueryParam)
 
--- | Various way to specify location.
+-- | Various ways to specify location.
 data Location
   = Name String -- ^ City name.
   | Coord Double Double -- ^ Geographic coordinates: latitude and longitude.
 
+addParam :: ToHttpApiData a => Text -> a -> Request -> Request
+addParam name = appendToQueryString name . Just . encodeUtf8 . toQueryParam
+
 instance HasClient m api => HasClient m (Location :> api) where
   type Client m (Location :> api) = Location -> Client m api
+  hoistClientMonad pm _ f cl = hoistClientMonad pm (Proxy :: Proxy api) f . cl
   clientWithRoute pm Proxy req loc =
     clientWithRoute pm (Proxy :: Proxy api) (addParams loc req)
     where
-      addParams (Name q) = appendToQueryString "q" (Just $ toQueryParam q)
-      addParams (Coord lat lon) =
-        appendToQueryString "lat" (Just $ toQueryParam lat) .
-        appendToQueryString "lon" (Just $ toQueryParam lon)
-  hoistClientMonad pm _ f cl =
-    \a -> hoistClientMonad pm (Proxy :: Proxy api) f (cl a)
+      addParams (Name q) = addParam "q" q
+      addParams (Coord lat lon) = addParam "lat" lat . addParam "lon" lon
diff --git a/lib/Web/OpenWeatherMap/Types/Main.hs b/lib/Web/OpenWeatherMap/Types/Main.hs
--- a/lib/Web/OpenWeatherMap/Types/Main.hs
+++ b/lib/Web/OpenWeatherMap/Types/Main.hs
@@ -11,12 +11,14 @@
 
 {-# ANN module "HLint: ignore Use camelCase" #-}
 
-data Main = Main
-  { temp :: Double
-  , pressure :: Double
-  , humidity :: Double
-  , temp_min :: Double
-  , temp_max :: Double
-  , sea_level :: Maybe Double
-  , grnd_level :: Maybe Double
-  } deriving (Show, Generic, FromJSON)
+data Main =
+  Main
+    { temp :: Double
+    , pressure :: Double
+    , humidity :: Double
+    , temp_min :: Double
+    , temp_max :: Double
+    , sea_level :: Maybe Double
+    , grnd_level :: Maybe Double
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Sys.hs b/lib/Web/OpenWeatherMap/Types/Sys.hs
--- a/lib/Web/OpenWeatherMap/Types/Sys.hs
+++ b/lib/Web/OpenWeatherMap/Types/Sys.hs
@@ -9,8 +9,10 @@
 
 import Data.Aeson (FromJSON)
 
-data Sys = Sys
-  { country :: Maybe String
-  , sunrise :: Int
-  , sunset :: Int
-  } deriving (Show, Generic, FromJSON)
+data Sys =
+  Sys
+    { country :: Maybe String
+    , sunrise :: Int
+    , sunset :: Int
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Weather.hs b/lib/Web/OpenWeatherMap/Types/Weather.hs
--- a/lib/Web/OpenWeatherMap/Types/Weather.hs
+++ b/lib/Web/OpenWeatherMap/Types/Weather.hs
@@ -9,9 +9,11 @@
 
 import Data.Aeson (FromJSON)
 
-data Weather = Weather
-  { id :: Int
-  , main :: String
-  , description :: String
-  , icon :: String
-  } deriving (Show, Generic, FromJSON)
+data Weather =
+  Weather
+    { id :: Int
+    , main :: String
+    , description :: String
+    , icon :: String
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/lib/Web/OpenWeatherMap/Types/Wind.hs b/lib/Web/OpenWeatherMap/Types/Wind.hs
--- a/lib/Web/OpenWeatherMap/Types/Wind.hs
+++ b/lib/Web/OpenWeatherMap/Types/Wind.hs
@@ -9,7 +9,9 @@
 
 import Data.Aeson (FromJSON)
 
-data Wind = Wind
-  { speed :: Double
-  , deg :: Double
-  } deriving (Show, Generic, FromJSON)
+data Wind =
+  Wind
+    { speed :: Double
+    , deg :: Double
+    }
+  deriving (Show, Generic, FromJSON)
diff --git a/openweathermap.cabal b/openweathermap.cabal
--- a/openweathermap.cabal
+++ b/openweathermap.cabal
@@ -1,67 +1,75 @@
-name: openweathermap
-version: 0.2.0
-synopsis: Access data at OpenWeatherMap
-description: Client library and command-line utility to access
-  OpenWeatherMap https://openweathermap.org
-license: PublicDomain
-license-file: LICENSE
-author: Igor Pashev
-maintainer: Igor Pashev <pashev.igor@gmail.com>
-copyright: 2017, Igor Pashev <pashev.igor@gmail.com>
-category: Web
-build-type: Simple
-extra-source-files: README.md ChangeLog.md
-cabal-version: 1.20
+cabal-version:      1.20
+name:               openweathermap
+version:            0.3.0
+license:            PublicDomain
+license-file:       LICENSE
+maintainer:         Igor Pashev <pashev.igor@gmail.com>
+author:             Igor Pashev
+synopsis:           Access data at OpenWeatherMap
+description:
+    Client library and command-line utility to access
+    OpenWeatherMap https://openweathermap.org
 
+category:           Web
+build-type:         Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
 source-repository head
-  type: git
-  location: https://github.com/ip1981/openweathermap.git
+    type:     git
+    location: http://git.pashev.ru/openweathermap
 
 flag cmd
-  description: Build a command-line utility.
-  default: True
+    description: Build a command-line utility.
 
 library
-  default-language: Haskell2010
-  ghc-options: -Wall
-  hs-source-dirs: lib
-  build-depends:
-      base >= 4.9 && < 5
-    , aeson
-    , http-api-data
-    , http-client
-    , servant
-    , servant-client >= 0.16
-    , servant-client-core
-  exposed-modules:
-     Web.OpenWeatherMap.API
-     Web.OpenWeatherMap.Client
-     Web.OpenWeatherMap.Types.City
-     Web.OpenWeatherMap.Types.Clouds
-     Web.OpenWeatherMap.Types.Coord
-     Web.OpenWeatherMap.Types.CurrentWeather
-     Web.OpenWeatherMap.Types.Forecast
-     Web.OpenWeatherMap.Types.ForecastWeather
-     Web.OpenWeatherMap.Types.Location
-     Web.OpenWeatherMap.Types.Main
-     Web.OpenWeatherMap.Types.Sys
-     Web.OpenWeatherMap.Types.Weather
-     Web.OpenWeatherMap.Types.Wind
+    exposed-modules:
+        Web.OpenWeatherMap.API
+        Web.OpenWeatherMap.Client
+        Web.OpenWeatherMap.Formulas
+        Web.OpenWeatherMap.Types.City
+        Web.OpenWeatherMap.Types.Clouds
+        Web.OpenWeatherMap.Types.Coord
+        Web.OpenWeatherMap.Types.CurrentWeather
+        Web.OpenWeatherMap.Types.Forecast
+        Web.OpenWeatherMap.Types.ForecastWeather
+        Web.OpenWeatherMap.Types.Location
+        Web.OpenWeatherMap.Types.Main
+        Web.OpenWeatherMap.Types.Sys
+        Web.OpenWeatherMap.Types.Weather
+        Web.OpenWeatherMap.Types.Wind
 
-executable openweathermap
-  default-language: Haskell2010
-  ghc-options: -Wall -static
-  hs-source-dirs: cmd
-  main-is: Main.hs
-  other-modules: Print
-  if flag(cmd)
+    hs-source-dirs:   lib
+    default-language: Haskell2010
+    ghc-options:      -Wall
     build-depends:
-        base >= 4.9 && < 5
-      , directory
-      , openweathermap
-      , optparse-applicative >= 0.13.0.0
-      , time
-      , xdg-basedir
-  else
-    buildable: False
+        base >=4.9 && <5,
+        aeson -any,
+        bytestring -any,
+        http-api-data -any,
+        http-client-tls -any,
+        servant -any,
+        servant-client >=0.19,
+        servant-client-core -any,
+        text -any
+
+executable openweathermap
+    main-is:          Main.hs
+    hs-source-dirs:   cmd
+    other-modules:    Print
+    default-language: Haskell2010
+    ghc-options:      -Wall -static
+
+    if flag(cmd)
+        build-depends:
+            base >=4.9 && <5,
+            directory -any,
+            openweathermap -any,
+            optparse-applicative >=0.13.0.0,
+            time -any,
+            xdg-basedir -any
+
+    else
+        buildable: False