Understanding Spring 2018 Start Dates
To answer how many days until Spring 2018, you first need to define which spring you mean. Astronomical spring in 2018 began on the vernal equinox, which occurred on March 20, 2018 at 16:15 UTC. Meteorological spring follows fixed three-month blocks and started on March 1, 2018. The number of days until spring depends on your reference point and which definition you adopt. This guide explains both methods, so you can apply the logic to any year.
Astronomical Spring 2018 Calculation
What Is the Vernal Equinox?
The astronomical start of spring is the vernal equinox, when day and night are nearly equal. In 2018, this happened on March 20. Before that date, astronomical spring had not yet begun. If you were counting from the start of winter (December 21, 2017), the interval to astronomical spring is exact and verifiable.
Counting Days to March 20, 2018
Counting forward from the December solstice (December 21) to March 20 yields 89 days in a standard Gregorian calendar. This period includes 31 days in December after the solstice, 31 in January, 28 in February (2018 was not a leap year), and 19 days in March up to the 20th. This is the most commonly referenced answer for how many days until spring 2018 from the astronomical winter start.
- December 21 to December 31: 11 days
- Full January: 31 days
- Full February: 28 days
- March 1 to March 20: 20 days
Meteorological Spring 2018
Fixed Seasonal Blocks
Meteorological spring is simpler for planning: it always starts on March 1 and ends on May 31. This system divides the year into four equal seasons of three months each, based on the Gregorian calendar, so the start date does not change year to year.
Counting to March 1
From the December solstice (December 21) to March 1 is 71 days. This includes 10 remaining days in December, 31 in January, and 28 in February. Many organizations use this definition for seasonal statistics and reporting because it aligns neatly with monthly intervals.
| Date or Period | Days from Dec 21, 2017 | Notes |
|---|---|---|
| March 1, 2018 (Meteorological Spring) | 71 days | Fixed seasonal start |
| March 20, 2018 (Astronomical Spring) | 89 days | Vernal equinox, astronomical definition |
How to Count Days Until a Future Spring
Choose Your Definition
For any future year, decide whether you want the astronomical or meteorological start. Astronomical dates shift slightly each year (usually by a day or two) due to calendar-month mismatches with the solar year. Meteorological dates are static, making them easier for year-over-year comparisons in temperature or climate data.
Practical Calculation Steps
- Identify the start date of spring under your chosen definition.
- Determine today’s date or your reference date.
- Count full days between the two dates, including the start date if you are measuring time until the beginning of that day.
Common Use Cases and Why Precision Matters
Gardening and Agriculture
Gardeners often align planting schedules with meteorological spring for predictability, while phenological events like flowering may track astronomical dates tied to daylight and temperature shifts.
Climate and Data Reporting
Meteorological seasons provide consistent 90–92 day windows, which are valuable for comparing datasets across years. Astronomical seasons reflect subtle changes in the timing of daylight and celestial events.
Education and Planning
For schools and event planners, knowing how many days until spring 2018 in either definition helps with scheduling terms, festivals, and outdoor activities with reliable lead time.
Key Takeaways
- Astronomical spring 2018 began on March 20, 2018, which is 89 days from the December 21 solstice.
- Meteorological spring begins on March 1, 2018, which is 71 days from the December 21 solstice.
- For future planning, define which spring you need and count days to the appropriate start date using a calendar or date tool.
Reliable Tools for Day Counting
Use built-in calendar applications, spreadsheet date functions, or reputable online calculators to verify day counts. Always confirm whether a tool uses astronomical or meteorological definitions to avoid off-by-one errors, especially around transitions in March.