Chronology of Pacific Islands Forum Metrication:

Pacific Islands Forum (PIF)

NIU Time Zone -11 Niuē (Niue) [NZL] Alofi
Metric System Legal: 1925
International System Adoption: 1969
Self-Governing State in Free Association with New Zealand

COK Time Zone -10 Cook Islands [NZL] Avarua
Metric System Legal: 1925
International System Adoption: 1969
Island Country in Free Association with New Zealand
pacificislands.com/cook-islands/cook-islands-faq.asp#Measure
6. What is the measurement system?
Cook Islanders use the metric system for weights and measures and the Celsius scale for measuring temps.

NZL Time Zone +12 New Zealand Wellington
Metric System Legal: 1925 – New Zealand Authorizing use of metric system of weights and measures in 1925
International System Adoption: 1969
United Nations Member: 24 Oct 1945

AUS Capital Time Zone +10 Australia Canberra
Metric System Legal: 1947; see MetricPioneer.com/Australia for more detail
International System Adoption: 1961 and 1970
Compulsory Metric Implementation: 1988
United Nations Member: 1 Nov 1945

PNG Time Zone +10 Papua New Guinea Port Moresby
International System Adoption: 1970
United Nations Member: 10 Oct 1975
According Going Metric: an Analysis of Experiences in Five Nations and their Implications for U. S. Educational Planning – National Institute of Education Project No. 3-2173 by Albert B. Chalupsky and Jack J. Crawford and Edwin M. Carr 1974: An Ordinance of Papua-New Guinea, No. 78 of 1970, assented to on 19 October 1970, makes a similar provision to that of the Metric Conversion Act.

SLB Time Zone +11 Solomon Islands Honiara
International System Adoption: 1970
United Nations Member: 19 Sep 1978

FJI Time Zone +12 Fiji Suva
International System Adoption: 1972
United Nations Member: 13 Oct 1970

NRU Time Zone +12 Naoero (Nauru) Yaren District
International System Adoption: 1973-80
United Nations Member: 14 Sep 1999

TON Time Zone +13 Tonga Nuku’alofa
International System Adoption: 1975
United Nations Member: 14 Sep 1999

TUV Time Zone +12 Tuvalu Funafuti
International System Adoption: 1978
United Nations Member: 5 Sep 2000

KIR Time Zone +12, +13, +14 Kiribati Tarawa
International System Adoption: 1984
United Nations Member: 14 Sep 1999

FSM Time Zone +10 and +11 Federated States of Micronesia Palikir
International System Legal: 1986
International System Adoption: Incomplete
Compulsory Metric Implementation: ____
United Nations Member: 17 Sep 1991

MHL Time Zone +12 Marshall Islands Majuro
International System Legal: 1986
International System Adoption: Incomplete
Compulsory Metric Implementation: ____
United Nations Member: 17 Sep 1991

VUT Time Zone +11 Vanuatu Port Vila
International System Adoption: 1988
United Nations Member: 15 Sep 1981

PLW Time Zone +9 Belau (Palau) Melekeok
International System Legal: 1994
International System Adoption: Incomplete
Compulsory Metric Implementation: ____
United Nations Member: 15 Dec 1994

WSM Time Zone +13 Samoa Apia
International System Adoption: Incomplete
Compulsory Metric Implementation: ____
United Nations Member: 15 Dec 1976
frommers.com/destinations/samoa/684049
Weights & Measures — Samoa is officially on the metric system, but in their everyday lives, many residents still calculate distances by the British system used in American Samoa and in the United States. Speed limits are posted in miles per hour, and the speedometers of many local vehicles (most of which have the steering wheels on the left side, in the American and European fashion) show both miles per hour and kilometers per hour.

Click on the image of Earth here to see when metrication occurred in each country or territory on Earth: