Meteorological season of a date
Enter a date and a hemisphere to get its meteorological season: 2026-03-21 is spring in the north, while the same day is autumn in the south. Seasons follow fixed three-month blocks, not solstice dates. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Date
- 2026-03-21
- Hemisphere
- northern
- Year
- 2,026
- Month
- 3
- Day
- 21
- Month name
- March
Finding the meteorological season of a date is a climate-style question, not an astronomy puzzle. Weather services and monthly climate normals split the year into four fixed three-month blocks, so the answer depends on the calendar month and on which hemisphere you care about—not on the exact minute of a solstice. This tool takes an explicit ISO date in year-month-day form, a northern or southern hemisphere flag, and returns the season key, a title-cased label, the three months that define that season under the meteorological convention, and a short step trace of the classification. Computation is deterministic from your inputs alone: no host clock, no random seed, and no outbound network.
Fixed three-month meteorological boundaries by hemisphere
Meteorological seasons are defined as four consecutive three-month blocks that align with monthly climate statistics rather than with the drifting calendar days of solstices and equinoxes. In the northern hemisphere the blocks are winter in December, January, and February; spring in March, April, and May; summer in June, July, and August; and autumn in September, October, and November. In the southern hemisphere the same months invert: December through February is summer, March through May is autumn, June through August is winter, and September through November is spring.
That inversion is physical—Earth’s axial tilt puts opposite hemispheres into opposite solar seasons on the same calendar day—so a tool that assumed northern summer for every July would mislabel winter conditions across much of the southern world. Classification depends only on the month number once the hemisphere is fixed: any valid day in July maps to northern summer and southern winter. Season keys are stable English machine labels—winter, spring, summer, and autumn—chosen because autumn is the term preferred in international meteorology even where everyday speech says fall.
The day component of a valid date is still validated as a real Gregorian day so that impossible inputs never slip through to a season guess.
Practical tips, limits, and when to use this tool
Build a small known set for regression: a northern March date that must return spring, the same calendar day with southern hemisphere that must return autumn, a December pair that flips winter versus summer, and a deliberate failure with hemisphere set to something other than northern or southern. Round-trip checks are simple: extract the month, apply the three-month meteorological table for that hemisphere, and confirm the published season key. Year bounds stop at nine thousand nine hundred ninety-nine so four-digit ISO strings stay well defined for this product surface.
This landing targets people searching for the meteorological season of a date, fixed-month climate seasons, or northern versus southern season tables; it is not an astronomical solstice calculator, not a weekday tool, and not an age or business-day calculator.
What you can do with it
Climate education and worksheets
Teachers generate deterministic meteorological season labels for a list of ISO dates and both hemispheres without relying on the host clock or astronomy tables.
Travel and campaign localization
Marketers label December offers as summer for southern destinations and winter for northern ones using the same date string and an explicit hemisphere flag.
FAQ
What is the meteorological season of a date?
It is the climate-style season for that calendar month under fixed three-month blocks: in the north, winter is Dec–Feb, spring Mar–May, summer Jun–Aug, autumn Sep–Nov. The southern hemisphere uses the inverted mapping.
Why must I specify a hemisphere?
The same calendar month is opposite seasons on opposite sides of the equator. Without northern or southern, any single answer would be wrong for half the planet.
Is this the same as astronomical seasons?
No. Astronomical seasons start at solstices and equinoxes that shift by day and year. This tool uses fixed meteorological months only.
Is the meteorological season tool free?
The browser tool is free and runs locally.
Which months belong to each meteorological season?
In the northern hemisphere, winter runs from December to February, spring from March to May, summer from June to August and autumn from September to November. In the southern hemisphere the same blocks swap, so December to February is summer.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/date/meteorological-season \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"date":"2026-03-21","hemisphere":"northern"}'const res = await fetch("https://api.kit.forhosting.com/date/meteorological-season", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"date": "2026-03-21",
"hemisphere": "northern"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/date/meteorological-season",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"date": "2026-03-21",
"hemisphere": "northern"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/date/meteorological-season", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"date":"2026-03-21","hemisphere":"northern"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"date":"2026-03-21","hemisphere":"northern"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/date/meteorological-season", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"date": "2026-03-21",
"hemisphere": "northern"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "date.meteorological_season",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
year_min | 1 |
year_max | 9999 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Invalid dates and hemispheres other than northern or southern fail with invalid_input instead of inventing a season.
How to call the API and read the response
Extended timestamps with a time of day or a trailing Z are rejected so that timezone midnights cannot rewrite the calendar day behind your back. The hemisphere field also accepts hemi or region; after trimming and lowercasing it must resolve to northern or southern. Send a JSON body with two required string fields: date and hemisphere. The date field also accepts the aliases iso_date, value, or day, and must match exactly four digits, hyphen, two digits, hyphen, two digits for a real Gregorian day in the inclusive year range from one through nine thousand nine hundred ninety-nine. Short form aliases north, south, n, s, nh, and sh are accepted for compact forms and scripts, while strings such as east, equator, tropical, or both return invalid_input. On success the body echoes the canonical date string, year, month, day, and English month_name; normalizes hemisphere; sets convention to meteorological; sets season to the lowercase key and season_label to the title-cased form; lists season_months as the three month numbers for that block; and includes a human-readable message plus an ordered steps array that restates the parse and table lookup. Missing fields, wrong types, bad date shape, out-of-range years, impossible days such as a non-leap twenty-ninth of February, and invalid hemispheres all fail closed with invalid_input and are never billed. Pricing is a flat $0.002 per successful request with unit item.
Practical tips, limits, and when to use this tool
Prefer the primary field names date and hemisphere when you control the client; keep aliases for compatibility with forms that already label controls iso_date or region. Failed tasks that return invalid_input do not consume prepaid balance, so exploratory scripts that deliberately probe bad hemispheres or impossible dates remain cheap while you wire integrations.
Integration use cases
Seasonal product and UI fixtures
Engineering teams pin golden JSON for theme switches and content calendars so northern and southern builds never disagree on a fixed-month season.
Technical questions
Which hemisphere values are accepted?
northern and southern (case-insensitive). Short aliases north, south, n, s, nh, and sh are accepted. Anything else returns invalid_input.