平年値（旬ごとの値）
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天塩（留萌地方) 平年値（旬ごとの値）
| 要素 | 降水量 (mm) | 平均気温 (℃) | 日最高気温 (℃) | 日最低気温 (℃) | 平均風速 (m/s) | 日照時間 (h) | 降雪の深さ合計 (cm) | 最深積雪 (cm) | |
|---|---|---|---|---|---|---|---|---|---|
| 統計期間 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | 1991～ 2020 | |
| 資料年数 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | |
| 1月 | 上旬 | 17.0 | -4.4 | -1.5 | -8.6 | 4.5 | 11.8 | 70 | 57 |
| 中旬 | 14.1 | -5.8 | -2.8 | -10.4 | 4.1 | 19.0 | 72 | 65 | |
| 下旬 | 13.5 | -5.8 | -2.6 | -10.8 | 4.3 | 21.9 | 78 | 70 | |
| 2月 | 上旬 | 9.9 | -6.3 | -2.7 | -11.8 | 4.1 | 25.1 | 60 | 73 |
| 中旬 | 11.0 | -5.2 | -2.0 | -10.3 | 4.4 | 24.1 | 62 | 77 | |
| 下旬 | 10.7 | -4.2 | -0.4 | -10.3 | 4.3 | 29.5 | 45 | 75 | |
| 3月 | 上旬 | 9.8 | -3.4 | 0.0 | -8.5 | 4.7 | 38.9 | 47 | 71 |
| 中旬 | 13.5 | -1.2 | 2.1 | -6.0 | 4.7 | 44.0 | 39 | 63 | |
| 下旬 | 11.2 | 0.4 | 3.5 | -4.1 | 4.6 | 55.4 | 32 | 48 | |
| 4月 | 上旬 | 10.5 | 2.6 | 6.0 | -1.8 | 4.6 | 56.2 | 10 | 21 |
| 中旬 | 16.6 | 4.2 | 8.1 | -0.4 | 4.7 | 55.5 | 3 | 3 | |
| 下旬 | 14.4 | 6.2 | 10.4 | 1.1 | 4.7 | 54.7 | 1 | 0 | |
| 5月 | 上旬 | 22.8 | 7.9 | 12.1 | 3.1 | 4.5 | 56.4 | 0 | 0 |
| 中旬 | 18.6 | 9.5 | 13.9 | 4.5 | 4.3 | 60.8 | 0 | 0 | |
| 下旬 | 19.8 | 11.3 | 15.8 | 6.1 | 4.0 | 68.1 | 0 | 0 | |
| 6月 | 上旬 | 17.6 | 12.4 | 17.0 | 7.2 | 3.6 | 53.4 | 0 | 0 |
| 中旬 | 19.1 | 13.9 | 18.3 | 9.4 | 3.5 | 45.8 | 0 | 0 | |
| 下旬 | 19.3 | 15.2 | 19.7 | 10.6 | 3.6 | 54.8 | 0 | 0 | |
| 7月 | 上旬 | 28.2 | 17.1 | 21.5 | 12.6 | 3.2 | 49.8 | 0 | 0 |
| 中旬 | 27.4 | 17.7 | 22.0 | 13.7 | 3.5 | 49.8 | 0 | 0 | |
| 下旬 | 53.6 | 19.4 | 23.4 | 15.6 | 3.5 | 53.0 | 0 | 0 | |
| 8月 | 上旬 | 32.3 | 19.9 | 23.8 | 15.9 | 3.4 | 51.4 | 0 | 0 |
| 中旬 | 47.5 | 19.6 | 23.7 | 15.4 | 3.2 | 48.9 | 0 | 0 | |
| 下旬 | 43.8 | 19.0 | 23.3 | 14.4 | 3.5 | 59.4 | 0 | 0 | |
| 9月 | 上旬 | 39.9 | 18.3 | 22.8 | 13.2 | 3.6 | 61.2 | 0 | 0 |
| 中旬 | 43.0 | 16.3 | 20.7 | 10.9 | 3.7 | 55.6 | 0 | 0 | |
| 下旬 | 41.2 | 14.1 | 18.9 | 8.2 | 3.8 | 57.3 | 0 | 0 | |
| 10月 | 上旬 | 48.4 | 12.4 | 16.9 | 6.7 | 4.1 | 49.1 | 0 | 0 |
| 中旬 | 39.6 | 10.6 | 14.4 | 5.6 | 4.7 | 40.1 | 0 | 0 | |
| 下旬 | 39.6 | 8.6 | 12.3 | 3.8 | 4.8 | 38.4 | 1 | 1 | |
| 11月 | 上旬 | 35.6 | 6.2 | 9.6 | 2.1 | 5.2 | 24.1 | 5 | 3 |
| 中旬 | 37.3 | 3.3 | 6.4 | -0.2 | 5.0 | 17.5 | 18 | 10 | |
| 下旬 | 28.9 | 1.1 | 4.1 | -2.1 | 5.3 | 14.0 | 26 | 12 | |
| 12月 | 上旬 | 22.2 | -1.1 | 1.7 | -4.3 | 5.2 | 9.1 | 49 | 23 |
| 中旬 | 21.4 | -2.7 | 0.0 | -6.1 | 4.9 | 10.1 | 69 | 37 | |
| 下旬 | 17.5 | -3.5 | -0.7 | -7.4 | 4.7 | 12.5 | 73 | 46 | |