平年値（年・月ごとの値）
 |
 |  |
 |  |  |  |  |
 |  |  |  |
八丈島（東京都) 平年値（年・月ごとの値） 主な要素
| 要素 | 気圧 | 降水量 | 気温 | 蒸気圧 | 相対湿度 | 風向・風速 | 日照時間 | 全天日射量 | 雪 | 雲量 | 大気現象 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 現地平均 (hPa) | 海面平均 (hPa) | 合計 (mm) | 平均 (℃) | 日最高 (℃) | 日最低 (℃) | 平均 (hPa) | 平均 (％) | 平均 (m/s) | 最多風向 | 合計 (時) | 平均 (MJ/㎡) | 降雪の深さ | 最深積雪 (cm) | 平均 | 雪日数 | 霧日数 | 雷日数 | ||
| 合計 (cm) | 日合計の最大 (cm) | ||||||||||||||||||
| 統計期間 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2009 | 1991～ 2009 | 1991～ 2009 | 1991～ 2009 | 1991～ 2009 | 2009～ 2020 | 2009～ 2020 | 1991～ 2009 |
| 資料年数 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 19 | 19 | 19 | 19 | 19 | 12 | 12 | 19 |
| 1月 | 997.5 | 1015.9 | 201.7 | 10.1 | 12.9 | 7.6 | 8.8 | 68 | 5.1 | 西 | 84.9 | 7.0 @ | 0 @ | 0 @ | 0 @ | 7.7 @ | 3.7 | 0.0 | 3.7 @ |
| 2月 | 997.6 | 1016.0 | 205.5 | 10.4 | 13.5 | 7.5 | 9.1 | 69 | 5.6 | 西 | 87.8 | 9.1 @ | 0 @ | 0 @ | 0 @ | 7.6 @ | 2.5 | 0.0 | 2.7 @ |
| 3月 | 996.9 | 1015.2 | 296.5 | 12.5 | 15.8 | 9.3 | 10.8 | 71 | 5.3 | 西 | 124.5 | 11.7 @ | 0 @ | 0 @ | --- @ | 7.6 @ | 0.7 | 0.6 | 3.1 @ |
| 4月 | 996.2 | 1014.2 | 215.2 | 15.8 | 18.9 | 12.9 | 14.1 | 77 | 4.8 | 西 | 139.4 | 15.1 @ | 0 @ | 0 @ | --- @ | 7.1 @ | 0.0 | 2.5 | 1.5 @ |
| 5月 | 994.5 | 1012.3 | 256.7 | 18.8 | 21.8 | 16.2 | 18.2 | 84 | 4.7 | 南西 | 148.5 | 15.6 @ | --- @ | --- @ | --- @ | 8.0 @ | 0.0 | 3.5 | 0.9 @ |
| 6月 | 991.9 | 1009.4 | 390.3 | 21.3 | 24.1 | 19.4 | 23.6 | 91 | 4.5 | 南西 | 87.1 | 13.5 @ | --- @ | --- @ | --- @ | 8.9 @ | 0.0 | 9.4 | 1.4 @ |
| 7月 | 992.5 | 1009.8 | 254.1 | 25.2 | 27.7 | 23.3 | 29.2 | 92 | 4.3 | 南西 | 137.3 | 15.6 @ | --- @ | --- @ | --- @ | 8.3 @ | 0.0 | 8.3 | 1.9 @ |
| 8月 | 993.0 | 1010.3 | 169.5 | 26.5 | 29.6 | 24.3 | 30.2 | 87 | 3.7 | 南西 | 185.9 | 17.8 @ | --- @ | --- @ | --- @ | 7.0 @ | 0.0 | 1.6 | 2.8 @ |
| 9月 | 994.6 | 1012.0 | 360.5 | 24.5 | 27.6 | 22.3 | 26.9 | 86 | 4.7 | 東北東 | 139.6 | 14.1 @ | --- @ | --- @ | --- @ | 7.4 @ | 0.0 | 1.0 | 3.0 @ |
| 10月 | 997.2 | 1014.9 | 479.1 | 21.0 | 23.8 | 18.7 | 20.4 | 82 | 5.6 | 東北東 | 107.1 | 10.3 @ | --- @ | --- @ | --- @ | 7.4 @ | 0.0 | 0.7 | 2.2 @ |
| 11月 | 999.4 | 1017.4 | 277.4 | 16.9 | 20.0 | 14.2 | 14.9 | 74 | 4.6 | 西 | 102.6 | 8.1 @ | 0 @ | 0 @ | --- @ | 7.2 @ | 0.0 | 0.1 | 2.3 @ |
| 12月 | 998.8 | 1017.1 | 200.2 | 12.7 | 15.6 | 9.9 | 10.5 | 69 | 5.1 | 西 | 100.4 | 7.0 @ | 0 @ | 0 @ | --- @ | 6.9 @ | 0.8 | 0.0 | 2.9 @ |
| 年 | 995.8 | 1013.7 | 3306.6 | 18.0 | 20.9 | 15.5 | 18.1 | 79 | 4.8 | 西 | 1445.0 | 12.1 @ | 0 @ | 0 @ | 0 @ | 7.6 @ | /// | 27.7 | 28.7 @ |
- 「@」の付いた値は、参考値です。平年差や平年比に利用できません。