今天是5月5日，立夏啦！从这一刻起，春天彻底和我们告别，夏天正式登场。立夏作为夏天打头阵的节气，可不只是宣告，夏天来了这么简单，老祖宗还流传下来一句，“今年三伏天热不热，就看立夏”，这让大家对今年三伏天的热度，充满好奇。
先来说说三伏天，它是一年里最热的时段，在农历小暑和处暑之间，分初伏、中伏和末伏。按照“夏至三庚数头伏”的算法，今年7月20日入伏，8月18日出伏，一共30天 。
那今年三伏天，到底有多热呢？其实古人早根据立夏当天的天气，总结出了一些预测经验。像“立夏晴，三伏热；立夏雨，九场雨”，意思是立夏这天要是大晴天，没有下雨，那接下来的三伏天就大概率干旱炎热；
要是立夏下雨，那后续降雨就会比较多，天气会闷热潮湿些。还有“立夏无雨三伏热”“立夏落雨要买伞”等说法，表达的也是类似意思，立夏没雨，三伏天热且易干旱；立夏有雨，三伏天降雨多相对凉爽。
今年立夏在农历四月初八，属于“月头”。民间有“立夏在月头，三伏热死牛”的说法，认为月初立夏对应的三伏天会酷热。
不过从现代气象统计来看，立夏日期和三伏天的气温，相关性不太明显，毕竟气候是个复杂的大系统，受大气环流、海洋温度等，好多因素共同影响 。
除了晴雨，立夏时的风力和风向，也能透露点三伏天的天气信息。北方有“立夏刮北风，伏里旱”的说法，要是立夏刮北风，三伏天，可能会干旱；而南方则是“立夏刮南风，伏里涝”，立夏刮南风，会带来暖湿气流，让三伏天，雨水偏多，出现闷热桑拿天。
另外，古人还会观察动植物的反应，来预判暑热。比如“立夏蝉早叫，三伏天里烤”，如果立夏前后蝉鸣提前，那可能预示着夏季温度偏高。
https://weibo.com/ttarticle/p/show?id=2309405162980945035461
https://weibo.com/ttarticle/p/show?id=2309405162981075058972
https://weibo.com/ttarticle/p/show?id=2309405162982987661570
https://weibo.com/ttarticle/p/show?id=2309405162983356498191
https://weibo.com/ttarticle/p/show?id=2309405162980437262684
https://weibo.com/ttarticle/p/show?id=2309405162981083447431
https://weibo.com/ttarticle/p/show?id=2309405162980714348658
https://weibo.com/ttarticle/p/show?id=2309405162983172210750
https://weibo.com/ttarticle/p/show?id=2309405162982987661533
https://weibo.com/ttarticle/p/show?id=2309405162983352565992
https://weibo.com/ttarticle/p/show?id=2309405162980865081700
https://weibo.com/ttarticle/p/show?id=2309405162983176405026
https://weibo.com/ttarticle/p/show?id=2309405162981062213695
https://weibo.com/ttarticle/p/show?id=2309405162981012144396
https://weibo.com/ttarticle/p/show?id=2309405162976180306064
https://weibo.com/ttarticle/p/show?id=2309405162980940841198
https://weibo.com/ttarticle/p/show?id=2309405162983247708614
https://weibo.com/ttarticle/p/show?id=2309405162983172211084
https://weibo.com/ttarticle/p/show?id=2309405162980659560770
https://weibo.com/ttarticle/p/show?id=2309405162982899318977
https://weibo.com/ttarticle/p/show?id=2309405162975651823915
https://weibo.com/ttarticle/p/show?id=2309405162921389850720
https://weibo.com/ttarticle/p/show?id=2309405162981473517805
https://weibo.com/ttarticle/p/show?id=2309405162981012144262
https://weibo.com/ttarticle/p/show?id=2309405162981078990944
https://weibo.com/ttarticle/p/show?id=2309405162978889564303
https://weibo.com/ttarticle/p/show?id=2309405162983067091014
https://weibo.com/ttarticle/p/show?id=2309405162982991855803
https://weibo.com/ttarticle/p/show?id=2309405162982895124730
https://weibo.com/ttarticle/p/show?id=2309405162980726669397
https://weibo.com/ttarticle/p/show?id=2309405162982987661583
https://weibo.com/ttarticle/p/show?id=2309405162981037048236
https://weibo.com/ttarticle/p/show?id=2309405162976981418222
https://weibo.com/ttarticle/p/show?id=2309405162980798234904
https://weibo.com/ttarticle/p/show?id=2309405162980441718795
https://weibo.com/ttarticle/p/show?id=2309405162982983467251
https://weibo.com/ttarticle/p/show?id=2309405162982798917740
https://weibo.com/ttarticle/p/show?id=2309405162982891192631
https://weibo.com/ttarticle/p/show?id=2309405162980655628509
https://weibo.com/ttarticle/p/show?id=2309405162980961550694
https://weibo.com/ttarticle/p/show?id=2309405162970710933597
https://weibo.com/ttarticle/p/show?id=2309405162980869275697
https://weibo.com/ttarticle/p/show?id=2309405162982798917749
https://weibo.com/ttarticle/p/show?id=2309405162980873470390
https://weibo.com/ttarticle/p/show?id=2309405162976716914858
https://weibo.com/ttarticle/p/show?id=2309405162980517216412
https://weibo.com/ttarticle/p/show?id=2309405162977056653405
https://weibo.com/ttarticle/p/show?id=2309405162980722475110
https://weibo.com/ttarticle/p/show?id=2309405162981083447330
https://weibo.com/ttarticle/p/show?id=2309405162976704594093
今年南方部分地区，已经出现早蝉，这是不是和全球变暖导致物候，提前有关呢？
国家气候中心预测，2025年厄尔尼诺现象，可能会持续，受它影响，我国中东部地区，夏季气温偏高的概率，比较大，华北、黄淮等地可能出现阶段性高温热浪。
从长期趋势看，近30年我国三伏天，平均高温日数呈上升趋势，极端高温事件，频率也在增加，这和全球变暖的“温室效应累加，”以及城市化的“热岛效应”，都脱不了干系 。
按照这些农谚和气候预测，今年三伏天，或许是北方高温强度大，南方闷热持续久。不过虽说农谚，是老祖宗长期观察自然，总结出来的宝贵经验。
但现代气候太复杂，受多种因素影响，仅靠立夏的情况，很难精准预测三伏天到底有多热。咱们还是得结合现代气象科技的预报，提前做好应对准备，不管三伏天是热还是相对凉爽，都能舒舒服服度过。
