Installation | Usage | Customization | History | License

Wttrin is a simple Emacs frontend for Igor Chubin’s popular Weather Web Service wttr.in.

” A change in the weather is sufficient to recreate the world and ourselves. ”

• Marcel Proust, The Guermantes Way

Wttrin is on MELPA and MELPA Stable, so I recommend adding a use-package declaration to your Emacs init file. Installing Wttrin, assigning a keybinding, and customizing the location list is as simple as adding the following code and evaluating it.

(use-package wttrin
  :ensure t
  :commands (wttrin)
  :bind ("C-c w" . wttrin)
  :custom
  (wttrin-default-locations '("Bondi Beach" "Taghazout" "Tamarindo" "Huntington Beach")))

With the cursor after the last closing parentheses, press “C-x C-e”. Emacs will start the install, assign the keybinding, set the location list, and you’ll be ready to go.

If you’re running Emacs 30 or later, you can install Wttrin directly from its Git repository using the built-in package-vc system. This is particularly handy if you want to track the latest development or contribute bug fixes.

(use-package wttrin
  :vc (:url "https://github.com/cjennings/emacs-wttrin" :rev :newest)
  :bind ("C-c w" . wttrin)
  :custom
  (wttrin-default-locations '("Jeffreys Bay" "Raglan" "Mundaka")))

The `:vc` keyword automatically handles installation from the repository and updates when you run `M-x package-vc-upgrade`, making it easy to stay current with the main branch.

For the Elisp hackers using Straight for lockfiles or for easy hacking on bug fix PRs, you probably don’t need me to tell you what to put in your Emacs init, but here it is anyway.

(straight-use-package
 '(wttrin :type git :host github :repo "cjennings/emacs-wttrin"))

If you typically use Quelpa to install from the bleeding edge, here’s what to put in your Emacs init:

(quelpa '(wttrin
          :fetcher github :repo "cjennings/emacs-wttrin"))
(define-key global-map (kbd "C-c w") 'wttrin)

Wttrin is pulled to MELPA repositories regularly, so using Quelpa for Wttrin may provide no advantage over use-package. Regardless, Wttrin’s main branch should always be stable, so you’ll be fine.

Wttrin has a dependency on xterm-color to colorize the weather display buffer. When installing from MELPA, xterm-color is automatically installed. For local development or manual installations, ensure xterm-color is available.

If you’re developing wttrin or using a local clone:

(use-package wttrin
  :load-path "/path/to/emacs-wttrin"
  :defer t
  :bind ("C-c w" . wttrin)
  :custom
  (wttrin-default-locations '("Your City" "Another City")))

Note: xterm-color loads automatically when needed. No special `:preface` or `:after` configuration required.

If you prefer not to use use-package:

1 - Ensure xterm-color is installed (it will auto-install from MELPA if available via package.el)

2 - Clone the wttrin repository:

git clone https://github.com/cjennings/emacs-wttrin.git

3 - Add to your Emacs init file:

(add-to-list 'load-path "/path/to/emacs-wttrin")
(require 'wttrin)
(define-key global-map (kbd "C-c w") 'wttrin)

4 - Evaluate the code with M-x eval-region ⏎ to load the package and set the keybinding.

Simply use the keybinding you assigned, or run `M-x wttrin` to display the weather. A list of locations will display.

Choose one, or for a quick one-time weather check, type a new location and ⏎ . After the weather is displayed, you can press `a` to check another location, `g` to refresh, or `q` to quit.

Wttrin can be customized using the built-in Emacs Customize interface. To do this, type M-x customize ⏎ wttrin ⏎ and use the UI. However, it’s more portable and reproducible to keep the customizations in your init file, so do that.

Note for Emacs 29+ users: The examples below use `setq`, which works for all Emacs versions. If you’re running Emacs 29.1 or later, you can use `setopt` instead, which provides type checking and runs any custom setter functions. Both work fine for Wttrin.

Most people will just want to add a bunch of cities to the location list. However, you should know you can check the weather for places that aren’t cities, so here’s an example showing several ways to add locations to Wttrin.

(setq wttrin-default-locations
      '("Berkeley, CA"            ;; City and State (to disambiguate)
        "Wellington, New Zealand" ;; City and Country Name
        "~Big+Ben"                ;; The Landmark in London, not whomever you're thinking of
        "70116"                   ;; Zip Code for the French Quarter, New Orleans
        "BCN"                     ;; Airport Code for Barcelona
        "41.89,12.48"))           ;; GPS Coordinates for Rome

Customizing ‘wttrin-default-languages’ allows users to tell Wttrin which language to request for the text it displays. For instance, this changes the language used for days of the week, periods of the day, and other related text.

Wttrin’s default is currently: “en-US,en;q=0.8,zh-CN;q=0.6,zh;q=0.4”,

This means Wttrin defaults to American English, then falls back to any other type of English, Simplified Chinese, then finally any other type of Chinese. Of course that doesn’t even begin to account for everyone’s use case, so here’s what you need to know to customize this.

Language codes usually follow the format of a primary language tag in lowercase (like “en” for English, “fr” for French, “zh” for Chinese), optionally with a region subtag in capitals (like “US” for United States or “CN” for China). If you use both, add a hyphen between them. You can enter just “en”, but you may want to enter “en-GB” to avoid seeing how we trash the King’s English on this side of the pond.

To have Wttrin render in Traditional Chinese:

(setq wttrin-default-languages '("Accept-Language" . "zh-TW"))

And to have Wttrin render in French:

(setq wttrin-default-languages '("Accept-Language" . "fr-FR"))

Where to look up language codes? The IETF’s BCP 47 official reference is online here. But those who were quick to open that link now know why I recommend this search interface.

The default font is “Liberation Mono” because it’s libre and ubiquitous on Linux distributions. Don’t worry, Emacs will find another monospaced font if that one’s not installed. However, if you need to use your favorite monospaced font so Wttrin blends in with the rest of your Emacs Feng Shui, here you go:

(setq wttrin-font-name "Hack Nerd Font Mono")

You can change the font size by changing the font height. The default is 110. Note that Emacs uses the “canonical character height”, which is 1/10th of a font point. For example, if you want a 12 point font size, you’d choose a font-height of 120.

(setq wttrin-font-height 120)

Wttrin’s default is to select the unit system appropriate for the location you query. Some may want the units they’re familiar for the weather in all locations.

(setq wttrin-unit-system "m") ;; for Metric units
(setq wttrin-unit-system "u") ;; for USCS/Imperial units
(setq wttrin-unit-system nil) ;; the default of using units appropriate for the queried location.

Wttrin caches weather data to reduce API calls and improve responsiveness. The cache holds data for 15 minutes by default, with a maximum of 50 entries. If you’re checking weather frequently or want longer cache times, you can adjust these:

(setq wttrin-cache-ttl (* 30 60))   ;; Cache for 30 minutes (in seconds)
(setq wttrin-cache-max-entries 100) ;; Store up to 100 cached locations

Wttrin can display current weather for your favorite location directly in the mode-line. The weather updates automatically in the background every 15 minutes, showing a color emoji weather icon with full details on hover.

To enable the mode-line weather display, set your favorite location and enable auto-start:

(use-package wttrin
  :ensure t
  :custom
  (wttrin-favorite-location "Berkeley, CA")
  (wttrin-mode-line-auto-enable t))

Alternatively, you can manually toggle the mode-line display:

(wttrin-mode-line-mode 1)  ;; Enable
(wttrin-mode-line-mode 0)  ;; Disable

• Mode-line icon: Shows just a color emoji (e.g., ☀️ 🌧️ ⛅)
• Tooltip: Hover for full details (location, temperature, conditions)
• Left-click: Open full weather buffer for your favorite location
• Right-click: Force refresh the weather data immediately
• Auto-refresh: Updates every 15 minutes automatically

You can customize several aspects of the mode-line weather display:

;; Set your favorite location (required for mode-line display)
(setq wttrin-favorite-location "New Orleans, LA")

;; Auto-enable mode-line weather on startup
(setq wttrin-mode-line-auto-enable t)

;; Adjust refresh interval (in seconds, default is 900 = 15 minutes)
(setq wttrin-mode-line-refresh-interval (* 10 60))  ;; Refresh every 10 minutes

;; Choose emoji font for color display (common options)
(setq wttrin-mode-line-emoji-font "Apple Color Emoji")   ;; macOS
(setq wttrin-mode-line-emoji-font "Noto Color Emoji")    ;; Linux (default)
(setq wttrin-mode-line-emoji-font "Segoe UI Emoji")      ;; Windows
(setq wttrin-mode-line-emoji-font nil)                   ;; Use default font

Note: If the weather emoji appears as a monochrome symbol instead of a color icon, try setting `wttrin-mode-line-emoji-font` to match a color emoji font installed on your system. Use `M-x fc-list` or check your system fonts to see what’s available.

If wttrin isn’t working as expected, enable debug mode to see detailed logging of what’s happening.

Important: The `wttrin-debug` variable must be set before wttrin loads, as it’s checked at load time to decide whether to load the debug module. Use `:preface` to set it before the package loads.

(use-package wttrin
  :ensure t
  :preface
  ;; Set debug BEFORE wttrin loads
  (setq wttrin-debug t)
  :custom
  (wttrin-favorite-location "Your City"))

❌ This will NOT work (debug set too late):

(use-package wttrin
  :ensure t
  :custom
  (wttrin-debug t)  ;; TOO LATE - wttrin already loaded!
  (wttrin-favorite-location "Your City"))

(use-package wttrin
  :ensure t
  :preface
  ;; Set debug BEFORE wttrin loads
  (setq wttrin-debug t)
  :custom
  (wttrin-favorite-location "Your City"))

Once debug mode is enabled, you can view the debug log:

M-x wttrin-debug-show-log

This shows a timestamped log of all wttrin operations:

• URL fetch attempts
• Data received (with byte counts)
• Mode-line display updates
• Emoji extraction
• Any errors encountered

When working correctly, the debug log looks like:

[11:51:46.490] mode-line-fetch: Starting fetch for Berkeley, CA
[11:51:46.490] mode-line-fetch: URL = https://wttr.in/Berkeley%2C%20CA?m&format=%l:+%c+%t+%C
[11:51:46.490] mode-line-fetch: Received data = "Berkeley, CA: ☀️ +62°F Clear"
[11:51:46.490] mode-line-display: Updating display with: "Berkeley, CA: ☀️ +62°F Clear"
[11:51:46.490] mode-line-display: Extracted emoji = "☀", font = Noto Color Emoji
[11:51:46.490] mode-line-display: Complete. mode-line-string set = YES

• xterm-color missing: Ensure xterm-color is installed (`M-x package-install RET xterm-color`). It loads automatically when wttrin displays weather.
• Debug not working: Remember to set `wttrin-debug t` before loading wttrin (use `:preface` in use-package)
• Mode-line not showing: Check `M-x wttrin-debug-show-log` to see if fetch succeeded
• No network access: Debug log will show “Network error” messages

Wttrin was originally the work of Carl X. Su and Ono Hiroko. All credit and appreciation for the original idea and code is theirs, not mine. Over time the package stopped working due to the inevitablity of bit-rot and Emacs’s own evolution. I loved using this package, so I adopted Wttrin to maintain and evolve for the Emacs community, and as thanks to the original authors.

Please consider this repository as Wttrin’s new home and I’ll throw out a welcome mat. I am grateful for any and all bug reports, enhancement requests, and PRs, so feel free to send them my way.

GPL-v3.0 or later