平年値（旬ごとの値）
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八丈島（東京都) 平年値（旬ごとの値）
| 要素 | 海面気圧 (hPa) | 降水量 (mm) | 平均気温 (℃) | 日最高気温 (℃) | 日最低気温 (℃) | 相対湿度 (%) | 平均風速 (m/s) | 日照時間 (時) | 全天日射量 (MJ/㎡) | 降雪の深さ合計 (cm) | 最深積雪 (cm) | 雲量 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 統計期間 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2009 | 1991～ 2009 | 1991～ 2009 | 1991～ 2009 | |
| 資料年数 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 19 | 19 | 19 | 19 | |
| 1月 | 上旬 | 1015.7 | 54.4 | 10.6 | 13.4 | 8.0 | 67 | 5.2 | 28.3 | 6.7 @ | 0 @ | --- @ | 7.3 @ |
| 中旬 | 1016.4 | 75.2 | 10.1 | 12.8 | 7.6 | 69 | 5.0 | 26.2 | 6.9 @ | 0 @ | --- @ | 7.7 @ | |
| 下旬 | 1015.8 | 72.1 | 9.6 | 12.4 | 7.1 | 68 | 5.1 | 30.4 | 7.3 @ | 0 @ | 0 @ | 7.9 @ | |
| 2月 | 上旬 | 1015.3 | 64.6 | 9.8 | 12.9 | 7.0 | 68 | 5.5 | 29.8 | 8.5 @ | 0 @ | 0 @ | 7.6 @ |
| 中旬 | 1015.9 | 74.1 | 10.4 | 13.6 | 7.6 | 68 | 5.6 | 32.3 | 9.5 @ | 0 @ | --- @ | 7.4 @ | |
| 下旬 | 1016.9 | 66.8 | 11.1 | 14.3 | 8.2 | 70 | 5.8 | 25.4 | 9.5 @ | 0 @ | --- @ | 7.8 @ | |
| 3月 | 上旬 | 1014.9 | 114.4 | 11.7 | 15.0 | 8.7 | 71 | 5.5 | 35.4 | 11.0 @ | 0 @ | --- @ | 7.3 @ |
| 中旬 | 1015.8 | 86.9 | 12.3 | 15.6 | 9.1 | 70 | 5.2 | 42.7 | 11.6 @ | 0 @ | --- @ | 7.6 @ | |
| 下旬 | 1015.0 | 95.3 | 13.3 | 16.6 | 10.1 | 72 | 5.1 | 46.4 | 12.4 @ | 0 @ | --- @ | 7.7 @ | |
| 4月 | 上旬 | 1014.8 | 69.4 | 14.6 | 17.8 | 11.7 | 75 | 4.9 | 45.5 | 14.8 @ | 0 @ | --- @ | 7.0 @ |
| 中旬 | 1013.8 | 79.7 | 15.9 | 19.0 | 13.1 | 78 | 4.9 | 44.1 | 14.4 @ | 0 @ | --- @ | 7.2 @ | |
| 下旬 | 1014.1 | 66.2 | 16.8 | 20.0 | 14.0 | 78 | 4.5 | 50.1 | 16.1 @ | --- @ | --- @ | 7.0 @ | |
| 5月 | 上旬 | 1013.5 | 85.6 | 18.0 | 21.0 | 15.5 | 84 | 4.8 | 45.7 | 15.3 @ | --- @ | --- @ | 7.9 @ |
| 中旬 | 1012.4 | 79.6 | 18.7 | 21.6 | 16.1 | 84 | 4.8 | 48.5 | 15.0 @ | --- @ | --- @ | 8.1 @ | |
| 下旬 | 1011.0 | 91.5 | 19.5 | 22.6 | 16.9 | 85 | 4.4 | 54.3 | 16.5 @ | --- @ | --- @ | 8.0 @ | |
| 6月 | 上旬 | 1010.4 | 105.0 | 20.1 | 23.3 | 17.9 | 87 | 4.4 | 40.7 | 15.7 @ | --- @ | --- @ | 8.4 @ |
| 中旬 | 1008.9 | 164.5 | 21.3 | 23.9 | 19.5 | 93 | 4.7 | 24.9 | 12.2 @ | --- @ | --- @ | 9.1 @ | |
| 下旬 | 1009.0 | 120.8 | 22.5 | 25.1 | 20.9 | 94 | 4.5 | 21.4 | 12.4 @ | --- @ | --- @ | 9.2 @ | |
| 7月 | 上旬 | 1009.6 | 112.6 | 24.1 | 26.4 | 22.4 | 94 | 4.6 | 29.5 | 13.3 @ | --- @ | --- @ | 9.0 @ |
| 中旬 | 1009.8 | 74.6 | 25.3 | 27.9 | 23.4 | 92 | 4.1 | 44.8 | 15.4 @ | --- @ | --- @ | 8.3 @ | |
| 下旬 | 1010.1 | 66.9 | 25.9 | 28.8 | 23.9 | 90 | 4.1 | 62.9 | 17.9 @ | --- @ | --- @ | 7.6 @ | |
| 8月 | 上旬 | 1010.5 | 56.6 | 26.4 | 29.6 | 24.4 | 88 | 3.6 | 63.2 | 18.9 @ | --- @ | --- @ | 7.1 @ |
| 中旬 | 1009.8 | 42.3 | 26.7 | 29.7 | 24.7 | 88 | 3.9 | 58.9 | 17.9 @ | --- @ | --- @ | 7.2 @ | |
| 下旬 | 1010.6 | 70.7 | 26.3 | 29.5 | 24.0 | 86 | 3.7 | 63.7 | 16.6 @ | --- @ | --- @ | 6.8 @ | |
| 9月 | 上旬 | 1010.6 | 121.3 | 25.6 | 28.8 | 23.4 | 88 | 4.3 | 53.3 | 15.6 @ | --- @ | --- @ | 7.4 @ |
| 中旬 | 1012.0 | 100.5 | 24.8 | 27.9 | 22.5 | 86 | 4.5 | 47.9 | 14.3 @ | --- @ | --- @ | 7.3 @ | |
| 下旬 | 1013.2 | 138.7 | 23.2 | 26.1 | 21.0 | 84 | 5.4 | 38.5 | 12.4 @ | --- @ | --- @ | 7.7 @ | |
| 10月 | 上旬 | 1013.9 | 179.5 | 22.4 | 25.3 | 20.1 | 85 | 5.4 | 37.0 | 11.1 @ | --- @ | --- @ | 7.6 @ |
| 中旬 | 1014.9 | 164.5 | 21.1 | 23.9 | 18.9 | 83 | 5.7 | 33.8 | 10.4 @ | --- @ | --- @ | 7.2 @ | |
| 下旬 | 1015.8 | 135.2 | 19.7 | 22.5 | 17.3 | 79 | 5.5 | 36.4 | 9.5 @ | --- @ | --- @ | 7.5 @ | |
| 11月 | 上旬 | 1017.3 | 83.8 | 18.3 | 21.5 | 15.5 | 75 | 4.6 | 36.4 | 8.9 @ | 0 @ | --- @ | 7.2 @ |
| 中旬 | 1017.2 | 113.6 | 16.8 | 19.9 | 14.1 | 74 | 4.6 | 33.3 | 8.1 @ | 0 @ | --- @ | 7.2 @ | |
| 下旬 | 1017.7 | 80.0 | 15.7 | 18.6 | 13.0 | 73 | 4.7 | 33.6 | 7.4 @ | --- @ | --- @ | 7.2 @ | |
| 12月 | 上旬 | 1017.6 | 78.5 | 14.1 | 17.0 | 11.3 | 71 | 4.9 | 33.5 | 7.2 @ | 0 @ | --- @ | 6.6 @ |
| 中旬 | 1017.6 | 58.1 | 12.5 | 15.3 | 9.8 | 68 | 5.1 | 31.9 | 7.0 @ | 0 @ | --- @ | 6.9 @ | |
| 下旬 | 1016.3 | 63.6 | 11.6 | 14.5 | 8.8 | 68 | 5.2 | 35.0 | 6.8 @ | 0 @ | --- @ | 7.1 @ | |
- 「@」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。