I looked it up because I'm starting to prepare for my Advanced certificate here in Canada - NOTAMS and METARS are the same format, since they're designed for all pilots.
So...
KORD - O'hare
291449Z - Day and time at UTC : day 29 14:49 zulu (09:49 in Chicago)
2915/3018 - no idea.. (I need to look that up, too)
34013G20KT - wind coming from 340 degrees. 13 knots gust of 20 knots.
P6SM - visibility is 6 miles (I have no idea what the P stands for)
SCT025 - scattered clouds at 2,500 feet
BKN250 - broken clouds at 25,000 feet
The METAR is similar...
KORD = O'Hare
291551Z = 29th day, 1551 UTC
10SM = visibility 10 statute miles
30008KT = wind from 300 degrees (West-northwest) at 8 knots
SCT030 = scattered clouds at 3,000 feet AGL
BKN200 = broken clouds at 20,000 feet AGL
25/14 = 25 degrees Celsius / dew point is 14 Celsius
A2981 = Altimeter (barometric pressure) 29.81 inches of mercury
RMK = Remarks
A02 = the station can report types of precipitation
SLP087 sea level pressure 987.0 millibar (you have to infer the hundreds and thousands places - pressure is always around 1000, so a low number like 123 would become 1012.3, and a high number like 876 would be 987.6
T02500139 = 25.0 Celsius, dewpoint 13.9 Celsius
$ = The system requires maintenance
A little meteorological aside ... If you see the barometric pressure dropping between METAR reports, there is an increased chance of precipitation. If it's rising, there is an increased chance that the weather will become, or remain, clear.
Thanks for asking the question - this is going to be helpful for me as I prepare for the Canadian Advanced RPAS pilot exam. ??