Help me understand this.  The weewx documentation says all data is stored in 
UTC time.  If that is true (and I believe it is) how does my imported data in 
Local Time get converted to UTC?  The only place where I can see that weewx 
knows my time zone is possibly the Longitude value in weewx.conf.  Is there 
some other place where a GMT offset is stored?  Does it look at the system 
clock offset?  I'm really curious about this.  Thanks.


On Wed, Jan 18, 2023, at 5:40 PM, gjr80 wrote:
> If that is local time then you are in luck and need do nothing special. 
> If it's GMT/UTC then wee_import cannot handle it as is; it will be 
> treated as local, there is no 'this_is_GMT' option in wee_import. 
> Having looked at the wee_import date-time routines the only possible 
> way to import a GMT/UTC type date-time is if the date-time data was 
> formatted as an epoch timestamp. That being said, it should be fairly 
> easy to implement a 'this_is_GMT' option to interpret the date-time 
> string as GMT/UTC rather than local time, there is sufficient support 
> for GMT/UTC in the python date time library without the need to include 
> timezone data. I'll add it to the list of wee_import ToDos.
>
> Gary
>
> On Thursday, 19 January 2023 at 10:15:11 UTC+10 Wayne wrote:
>> Here is a sample of a CSV format of my data: 
>> 
>> Time,TempOut,TempIn,HumOut,HumIn,Baro,Rain,Rate,Wind,WindDir,Gust,GustDir 
>> 2020-03-26 10:20:00,56.3,71.8,36.0,31.0,29.742,0.00,-327.68,10.0,270.0,22.0, 
>> 2020-03-26 10:30:00,56.8,70.2,35.0,29.0,29.739,0.00,-327.68,12.0,270.0,23.0, 
>> 2020-03-26 10:40:00,57.1,69.1,34.0,28.0,29.739,0.00,-327.68,12.0,247.5,22.0, 
>> 2020-03-26 10:50:00,57.4,69.0,33.0,27.0,29.742,0.00,-327.68,11.0,247.5,21.0, 
>> 2020-03-26 11:00:00,57.5,68.5,33.0,27.0,29.736,0.00,-327.68,13.0,247.5,23.0, 
>> 
>> My belief is that this is Local Time. There is no GMT offset nor timezone 
>> indicator. These are the first records that I captured at this particular 
>> location and I'm pretty sure I started this station around 10 AM and not 3 
>> AM local (if the value shown were UTC). Maybe others could confirm the 
>> WeatherLink application behavior. This data came from a Davis Weather 
>> Monitor II. I hope this helps. 
>> 
>> 
>> On Wed, Jan 18, 2023, at 4:19 PM, gjr80 wrote: 
>> > Short answer is it depends. What is the format of the date-time data in 
>> > your resulting CSV file? Is it straight date and time but in GMT, eg 
>> > '24-Jan-2023 18:25' or does it have some sort of timezone indicator 
>> > embedded eg '24-Jan-2023 18:25 GMT' or is an epoch timestamp eg 
>> > '1674548700'? WeeWX does not recognise timezones but the python 
>> > datetime calls used may support GMT. I will need to look at your data 
>> > and the wee_import date-time parsing routines to see what is possible. 
>> > 
>> > Gary 
>> > 
>> > On Thursday, 19 January 2023 at 08:41:35 UTC+10 Wayne wrote: 
>> >> I am looking into the process for converting my Davis weather archive 
>> >> files to be imported into weewx. If I'm not mistaken, Davis WeatherLink 
>> >> stores the timestamps in local time in the .wlk files. Accordingly, the 
>> >> application wlkReader creates a csv file also in the same local time 
>> >> format. 
>> >> 
>> >> The import config file used by the utility wee-import provides an option 
>> >> raw_datetime_format for defining the text date/time format in the csv 
>> >> input file. Although I don't see it explicitly discussed in the Utilities 
>> >> Guide, is there a format code which can be use in this option which 
>> >> applies a UTC offset conversion to the supplied local time? If so can you 
>> >> give an example of its usage? Otherwise the only other option I see is to 
>> >> manually convert the times in the input csv files to UTC prior to 
>> >> importing. I'm sure I am not the first user to encounter this issue! My 
>> >> thanks in advance. 
>> > 
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