I am developing a Weather Widget for an iOS app. Basically what this widget will do is allow the user to select a city and return it's current temperature and weather. The user can either refresh the widget or it can automatically update. But it also has to work offline, showing the last fetched weather and temperature and how long since it has been updated.

Question is, if I am making the widget change the background to a day/night theme based on the selected city's time. What would be the best approach if the widget has not been updated for 12 hrs and the temperature and weather when it was last updated and is being shown was at day time, and the current time the user is looking at the widget is at night time. Should I change the theme to night or day?

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2 Answers 2


I’m assuming by “night theme” you mean to present a pictorially accurate representation of the sky at a location, not make a screen that avoids frying the user’s eyes’ dark adaptation.

If the data is 12 hours old, show the sky at the chosen location as it was 12 hours ago –light if it was daylight, dark if it was night. This would constitute an important cue that the data is out of date (e.g., don’t trust that temperature).

Otherwise, users might be confused by the image that contradicts the text saying it’s conditions from a long time ago. If you say the data is 12 hours out of date but show a dark sky as it currently is at the location, users may think you're saying it was dark there 12 hours ago, and thus light now (assuming they don't figure how many time zones separate them from the location). Or, if users know it should be dark there now, and see you saying it was dark "12 hours ago," they may think the text is inaccurate and all the data is in fact up to date.


Let the local time (of the last known location) decide when to use the light or dark mode. If it is night, then use the dark theme, else use the light theme.

Consider WHY the user could benefit from a light or a dark theme. The main reason is that it is easier to take advantage of a light theme in daylight, and in the dark, you would possibly prefer a darker screen.

In my humble opinion, there is no correlation between when the data was updated and what theme to use.

Hope this helped you out.

Update width an example: Let's say that your last known location was London and now you're in New Yourk. In London, the sunset occurred at 18:00 local London time. Although you are in New York, when the local time In New York turns into 18:00, your widget should switch to dark mode.

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