{"id":190,"date":"2007-03-15T01:01:44","date_gmt":"2007-03-15T08:01:44","guid":{"rendered":"http:\/\/www.cicadamania.com\/cicadas\/2007\/03\/15\/cicada-emergence-formula\/"},"modified":"2026-02-08T21:13:09","modified_gmt":"2026-02-09T04:13:09","slug":"cicada-emergence-formula","status":"publish","type":"post","link":"https:\/\/www.cicadamania.com\/cicadas\/cicada-emergence-formula\/","title":{"rendered":"Periodical Cicada Emergence Formula"},"content":{"rendered":"<p>You could try this with northern Magicicada periodical cicadas, but I would avoid it for southern states like Louisiana (because you&#8217;ll get negative numbers, which will be confusing). Also, do not use temperature data from past years, because the weather is wildly variable and you&#8217;ll get a useless number.<\/p>\n<p><script src=\"\/js\/kritskytemp.js\" defer><\/script><\/p>\n<blockquote><p>\nGene Kritsky was nice enough to send a paper he wrote with a formula for predicting the emergence date. E = (19.465 &#8211; t)\/0.5136, where E = emergence start date in May and t = average April temperatures in &deg;Celsius. His formula worked like a charm for predicting the Brood X emergence in Cincinnati. 80% of his sites had begun the emergence on the predicted date of May 14th of that year. Also when the ground temperature reaches a consistent &deg;Celsius that is another good sign the emergence is about to begin. <\/p><\/blockquote>\n<p id=\"pickit\"><strong>Try it out:<\/strong><\/p>\n<form action=\"#\" style=\"border: 1px solid #cfc;background-color: #FFE;padding: 4px;\">\n<p><strong>Average Mean Temperature in Celsius in April:<\/strong> <input type=\"text\" size=\"6\" maxlength=\"6\" id=\"datetopick\"\/> (hint: use a site like <a href=\"http:\/\/www.weatherunderground.com\/\" target=\"_blank\" rel=\"noopener noreferrer\">Weather Underground<\/a> to find this info)<br \/><input type=\"submit\" value=\"Calculate the date\" onclick=\"datapicker();return false\" \/><\/p>\n<p><\/p>\n<p><strong>The date should be:<\/strong><span id=\"thedate\"><\/span> <\/p>\n<\/form>\n<p>Updated: we updated the form to accept 3 numbers past the decimal in case you have super-precise temperature information.<\/p>\n<p>To find the Average Mean Temperature in Celsius on the Weather Underground site:<\/p>\n<ol>\n<li>Go to the site<\/li>\n<li>Enter your zip code in the box labeled &#8220;Find the Weather for any City, State or ZIP Code, or Airport Code or Country&#8221;<\/li>\n<li>Find the section of the page labeled &#8220;History &#038; Almanac&#8221;, and click the &#8220;April Calendar View&#8221; link.<\/li>\n<li>Then scroll to the top of that page and you&#8217;ll find the info you need.<\/li>\n<\/ol>\n<p>Thanks to Roy Troutman and Gene.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>You could try this with northern Magicicada periodical cicadas, but I would avoid it for southern states like Louisiana (because you&#8217;ll get negative numbers, which will be confusing). Also, do not use temperature data from past years, because the weather is wildly variable and you&#8217;ll get a useless number. Gene Kritsky was nice enough to [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,155],"tags":[],"class_list":["post-190","post","type-post","status-publish","format-standard","hentry","category-magicicada","category-periodical"],"_links":{"self":[{"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/posts\/190","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/comments?post=190"}],"version-history":[{"count":0,"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/posts\/190\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/media?parent=190"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/categories?post=190"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cicadamania.com\/cicadas\/wp-json\/wp\/v2\/tags?post=190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}