Samsung
Weather Notifications in Status Bar auf Samsung
The weather entry in your Samsung status bar is generated by the Google app, which bundles local weather updates into its own notification channel. This is why the alert can appear even without a weather widget on your home screen, and why searching inside a weather app for an off switch leads nowhere.
Because the setting lives under the Google app itself, turning it off only affects this one notification type. Other Google alerts, such as search suggestions or account notices, stay untouched.
To disable it, go to Open the Settings ➔ Tap on Apps ➔ Tap on Google ➔ Tap on Notifications ➔ Enable or disable Current weather condition. Switching this toggle off stops the status bar entry immediately, without restarting the phone.
If you still see weather information after disabling this, check whether a separate weather widget or app is installed, since those run independent notification settings. Re-enabling the toggle brings the alert back the next time conditions change locally.