I have recently had to find references for this info, and I provide them below for you guys to see the answers. Don't forget, any country can deviate from these but must publish those deviations.
ATIS
2 minute average and magnetic
Reference for this (bizarrely) from: ICAO Annexe 11 ATS
4.3.7. L) surface wind direction (in degrees magnetic)
4.3.6.1 (See Note) surface wind direction and speed are to be averaged over 2 minutes
METAR
ICAO Annexe 3 Appendix 3 APP 3-6
4.1.3.1 The averaging period for surface wind observations shall be:
a) 2 minutes for local routine and special reports and for wind displays in air traffic services units; and
NOTE - In UK for small aerodromes with traffic <5700kg, the instant wind is usually given see UK AIP GEN 3.5 3.1.1)
b) 10 minutes for METAR and SPECI, except that when the 10-minute period includes a marked discontinuity in the wind direction and/or speed, only data occurring after the discontinuity shall be used for obtaining mean values; hence, the time interval in these circumstances shall be correspondingly reduced.
4.1.5.1 In local routine reports, local special reports, METAR and SPECI, the surface wind direction and speed shall be reported in steps of 10 degrees true