By default, Snowflake accounts have their timezone set to US/Pacific. Here is how to change that permanently at the account level. You can still override it for specific users or sessions.

Set the account’s default time zone to US Eastern:

use role ACCOUNTADMIN;  -- Must have ACCOUNTADMIN to change the setting.
alter account set TIMEZONE = 'America/New_York';
use role SYSADMIN;  -- (Best practice: change role when done using ACCOUNTADMIN)

Set the account’s default time zone to UTC (Universal Coordinated Time, also called Greenwich Mean Time, GMT, or Zulu Time):

use role ACCOUNTADMIN; 
alter account set TIMEZONE = 'Etc/UTC';
use role SYSADMIN;

A complete list of timezone is available here: https://en.wikipedia.org/wiki/List_of_tz_database_time_zones.