I see it as a tiny reminder of ‘your standard way is not everyone’s standard way’ (or to word it more petty ‘you confuse me, so I confuse you’), so I use the way of date (dd.mm.yy(yy)) and temperature (C) that is common here. It’s also the numbers one would experience here as a visitor (on screens and TV and newspapers and so on).
I don’t expect senders to change their local formats, but I also would not ‘translate’ given temperature, so that information is kind of lost on me.
I write date in my local format (so today is 12.04.23 on my cards, a little confusion is good for you 
) and temps in C if I remember (usually don’t write the temperature, but if I do the recipients can convert to F themselves if they want to).
Can you please post a link here?
I usually ask to Alexa which is temperature here in Celsius and in Farenheit and I put both of them if I am sending to USA.
But for example the date I use Spanish way with the name of the month in Spanish, both languages are similar names in months and I think it’s not so hard to know it.
A little bite of Spanish 
I’ll be honest, I am totally new at this, just this week received my two first postcards (mailed out 7 from the system and a few requests from the forums). Never even thought to date them – as far as temperatures - I’ve mentioned it being HOT - but never put a temp, Maybe I should start?
For non-domestic cards, I write out dates like “April 12, 2023” to avoid confusion. For temperature, I always put both Fahrenheit and Celsius. For U.S. cards, I just put Fahrenheit and usually write dates our way numerically (I sometimes write the full thing out of reflex).
I really appreciate it when a card from abroad includes Fahrenheit, to be honest. It’s an extra thoughtful touch. I’ve learned an easy working conversion to do in my head, but it’s nice that I don’t have to.
I’ve received some cards with distance travelled written in kilometers. It doesn’t really mean anything to me, to be honest, just like “Oh, that’s nice, a big number.” I don’t write distance myself. It’d take up too much space putting miles and kilometers anyway, because I wouldn’t want to leave miles out.
@mobi I do it the exact same way
I use the Celsius scale for temperature, since most other countries seem to use it, and it is very easy using the weather app on my phone. 90% of my cards go to Germany these days anyway, and I know it is used there.
For the date, I prefer this format: 12 April 2023. Seems more clear to me, and I learned to write it that way while living with a British family was I was young, I actually prefer it this way. So I write it this way for all my correspondence to anyone, including outside of PC.
I write out the month to avoid confusion, like lots of people here have said! So, 13 April 2023. I always put the temperature in Celsius but if I am writing a card to the US, I add a little C next to the temperature.
I use ID-Stickers - some of them have the weather on them some do not. The ones that give the option to write the temperature already have the °C printed on them so I just give the Celsius temperature. I do not write the weather if this is not meant to be written on the sticker.
The date I always write Day, Month, year but the month written as a word so today I would write 13 April, 2023 in English or 13. April 2023 in German. Even if I write the card in another language than English or German I use either of the formats. I also write the date if I do not use an ID Sticker
I changed my phone to display the temperature in C°
Since I’ve been writing it in my cards that way.
And I write out the month name to be clear.
Welcome to postcrossing.
Like with many things, it’s a mix of own style, common (expected) behaviour and fullfilling wishes if one self wishes to do so
So if you personally don’t care about temperature, don’t mention it. If you want to answer/follow such specific wishes, just do it. Or you decide/vary from card to card.
As for the date, I’d vote for writing it. It was and still is a very common habit, in many contextes even an obligation (tax office, working contract, bills, …).
Also here in postcrossing, I think more users like to see the date than are bothered by those few numbers/letters. Personally, I am always surprised if there is no date, but that also happens (22 of 133 received cards in 2023)
But again - if you don’t care or are bothered by it, just leave it and do it your own style
Thanks for the info. I’ll definitely start at least adding the date. 
For the date, I usually write it Day-Month-Year for everywhere but the US. When sending there, when I remember I write it in letters to avoid any confusion both to me and the receiver (i.e. 13th April 2023)
I always write the temperature in Celsius instead
I do this too: use “American” format, but write out the name of the month. I put temperature in Fahrenheit as well (e.g.: 78° F.). I’ve noticed many profiles ask for notes on my local culture, and the differences in date and temperature format are part of my country’s culture, so I share that. We can celebrate small differences and still bond over our love of postcards!
That’s a very good question. Usually I write the date as in France (Day, month, year) and the temperature in °C. But it would be better, it is true, to write according to the recipient. Now I would write the full date : 13 April 2023 (with the month in the recipient’s language). And I would try to think about writing the temperature in fahrenheit and Celsius for the USA.
FIRST: Welcome to Postcrossing!!! We’re generally a very friendly bunch who love all aspects of sending and receiving postcards!
I brought up this topic/poll just because I was curious about what other people did and why. And after reading the comments, I’m beginning to re-think how I want to pass on this info (time, climate). I’ve been with Postcrossing for a while and have changed a lot of what I first did as I received cards and thought, “That would look good. I should do that!”
So have fun with starting in Postcrossing and deciding different things that you want to do to make it yours.
I always write it American style even if it might be a bit confusing, like 4/3/23, because I figure it’s just part of the cultural exchange. And I also like to receive postcards with whatever format is used by the sender, whether that’s 12/25/23, 25/12/23, 2023 12/25, etc. But if someone has requested recipes, I always convert the units into metric for convenience.
As a Californian I always write metric and DD/MM/YYYY.
Everyone just knows what’s up
I have a rubber stamp that puts the date like 14 Apr 2023. And I don’t usually write the temperature, but when the recipient asks for it, I do it in Celsius.