... mir fällt dazu ein: ... as of 30 degrees Centigrade ...

Dictionary: as of

At 86 degrees (Fahrenheit) or higher ...

I'd say

... +30°C equate to +86°F ... - Correct! ... - ;-))

... the formula being:

[(X degrees Centigrade) divided by 5] times a factor 9 (plus 32 degrees) equals 'degrees Fahrenheit' ...

... here: [30/5] x 9 (+32) = 86[°F] ...

... und dieses '5/9' entspricht dem eigentlichen Verhältnis von 100°C/180°F für den Bereich zwischen
'schmelzendem Eis' (0°C / 32°F) und 'kochendem Wasser' (100°C / 212°F) ...

Why not stick to Celsius?

Re #4: ... eine rhetorische Frage an die Nation der USA ? ... - ;-)

... wir können m.E. ja schon dankbar sein, dass man dort die 'cps' [cycles per second] zugunsten der internationalen Einheit 'Hz' (Hertz) hat fallen lassen ... - ;-))

Wikin weiß: http://de.wikipedia.org/wiki/Heinrich_Hertz ...

Etwas OT : Ich les' gerade ein Buch (Krimi) von einem US-amerikanischen Autor ... der wechselt munter zwischen °C und °F hin und her ... ohne diese anzugeben ... er nennt nur die Zahlen ... und lässt die werte Leserschaft raten ...

#5 Nope. There is a lot of world outside the USA.

Re #4: because I felt like it.

.

Apart from dude's delightful switch to °F [which seems to have ruffled the feathers of a few here ,-) ], his comment in #2 makes a very good point.

While #1 ("as of") would likely be understood by many AE speakers and is in the standard online dictionaries, my impression has been that in reality it's not used as often and in quite the same way in AE as in BE.

Ich störe die Party ungern, aber: AnnaUK hat noch keine Rückmeldung gegeben ob Interpretation und Übersetzung (... or higher) inhaltlich überhaupt stimmen.
Entgegen der im Faden akzeptierten Auslegung ist nicht klar, was Ab 30° Celsius ... im OP tatsächlich bedeutet.

Der Kontext könnte auch so sein:
Bei normaler Betriebstemperatur von 120°C ist ein Service nicht möglich, aber nach dem Abstellen fällt die Temperatur rasch. Ab 30 Grad Celsius werden die Filter ausgestauscht.

Support Dude.

It's one of these cases that has me thinking "there must be a simple word for that", but there isn't. I'd say "If the temperature reaches 30°//At [temperatures of] 30° or higher" or similar. One of those rare instances of German brevity.

I wouldn't use "as of" in most (any?) contexts for this.

Was halten die native speakers von
at and above 30 degrees Celsius
at and below 30 degrees Celsius
??

Es finden sich Stellen für diese Formulierungen - allerdings nicht viele.
http://www.pubfacts.com/detail/19719660/Ecolo....
Temperature optima for photosynthetic activity were at and above 30 degrees C.
http://www.bluediamond.com/applications/in-th...
Many areas around the region reported readings at and below 30 degrees for several hours with coldest locations dropping to as low as 26 and 27 degrees.

"at and above" is fine, too. It's the same as "at or higher," and it's not any shorter. There other ways of saying this as well: "at or more," "at or warmer," etc. They all mean more or less the same.

I would have thought at or above rather than at and above.

And then of course there’s another can of worms: centigrade (#1, 3) vs. Celsius.

I certainly wouldn't use "as of" in this context. The only context I can think of for "as of" at the moment is dates.

Like Oxymorphon, I tend to think that "at or below 30°C" is more likely for replacement of filters, but without more info from AnnaUK, it's impossible to be sure.

Like Stravinsky, I find "at or above/below" more natural than "at and above/below".

>>I certainly wouldn't use "as of" in this context. The only context I can think of for "as of" at the moment is dates.

Ditto.

And while there is evidently some AE/BE difference on this point, I also wouldn't use centigrade (or Celsius) in English except in a scientific context. Especially in things like instruction manuals, you should definitely give temperatures in Fahrenheit, at least in parentheses.

I would also use 'at': at 86 degrees and up / and below.

#17: And while there is evidently some AE/BE difference on this point, I also wouldn't use centigrade (or Celsius) in English except in a scientific context. 
There certainly is some difference. In the UK Celsius is used as the official unit of measurement by the Met Office ( http://www.metoffice.gov.uk/about-us/units-of... ) so I would expect to see Celsius used in BE in both weather and scientific contexts. TV, radio and newspaper weather forecasts use °C (even though some forecasters will occasionally add something like "that's X° in Fahrenheit" when speaking).

In the UK Celsius is used as the official unit of measurement by the Met Office  
And even the Daily Telegraph does too - and that's saying something. ;-)