Crochet Temperature Blanket Guide & Colour Chart
A temperature blanket records a year of weather as a piece of fabric: one row for each day, the day's temperature deciding the colour. Almost every decision that matters is made before the first stitch, and this guide works each one through on a real year of daily readings rather than on a stock palette.
1. The year and the location. 2. High, low or mean — then never change it. 3. Where the band boundaries fall. 4. One row a day, two, or a square. 5. The finished length, checked against your row gauge before row one.
What a temperature blanket is
A temperature blanket maps a daily temperature to a colour band, and a colour band to a yarn. Each day becomes one row, one pair of rows or one square, so the calendar — not your pattern — determines the row count: 365 in a common year, 366 in a leap year.
That inversion is what makes the project unusual. In an ordinary blanket you choose the dimensions and the stitch count follows. Here the row count is fixed before you begin, and the only variable left to control the finished length is your row gauge.
Choose the year and the location
A year in progress means recording each day as it happens and living with the suspense; a past year means the whole record is available at once, so you can plan the exact yarn quantities and even see the finished design before starting. Past years also let you mark something specific — a birth year, the year you moved — which is often the better gift.
Location matters more than people expect. A reading from an airport weather station eight miles away is a genuine measurement, but it is not your garden: airports are open, exposed and often a degree or two different from a sheltered urban street. Pick one source and one location for the whole year, and note both alongside the blanket, because in five years nobody will remember which was used.
High, low or mean — the decision that changes the most
This is usually treated as a matter of taste. It is a much bigger decision than that, and a real year shows why.
Below is a year of daily temperatures for London in 2025, taken from the Open-Meteo historical archive and sorted into the same six bands three separate times — once by daily high, once by daily low, once by daily mean.
| Band | Same band in °F | Days as high | Days as low | Days as mean |
|---|---|---|---|---|
| under 4 °C | under 39.2 °F | 11 | 80 | 38 |
| 4 to 8 °C | 39.2 to 46.4 °F | 47 | 74 | 50 |
| 8 to 12 °C | 46.4 to 53.6 °F | 49 | 88 | 77 |
| 12 to 16 °C | 53.6 to 60.8 °F | 77 | 85 | 89 |
| 16 to 20 °C | 60.8 to 68 °F | 72 | 37 | 70 |
| 20 and over °C | 68 and over °F | 109 | 1 | 41 |
Read the bottom row across. The warmest band is nearly a third of the blanket if you track highs, and a single row if you track lows. Neither is more correct, but they are not interchangeable, and a blanket planned around one choice cannot be switched to another halfway through without destroying the record.
One practical difference is worth knowing: across this year the daily high and daily low differ by an average of 7.0 °C, and on the most volatile day — 1 May 2025 — by 16.7 °C. Tracking the mean smooths that swing away; tracking highs or lows keeps it.
Designing the colour bands
Six evenly spaced bands is the usual starting point, and it is worth questioning, because equal width does not produce equal presence.
Cutting London's 2025 mean temperatures into six equal-width bands of 5.07 °C gives the busiest band 106 days and the quietest 12 — an imbalance of nearly nine to one. Cutting instead at the points that split the year into six equal groups gives every colour between 57 and 64 days.
Both are defensible. Equal width is an honest picture of the temperature scale; equal frequency is an honest picture of the year. What is not defensible is inheriting a band scale from a blanket made in a different climate and then wondering why two of your colours never appear. Set the bands from the range you are actually recording.
Choosing the colours themselves
Band boundaries are arithmetic; the palette is design, and it has three constraints that catch people out.
Adjacent bands must differ in lightness, not just in hue. Two colours that read as clearly different side by side in daylight can be identical in value, and where that happens the boundary between them vanishes in the finished fabric — and in every photograph of it. Photograph your yarn together and convert the image to greyscale: if neighbouring bands merge, change one.
The yarn has to exist for twelve months. A year-long project outlasts plenty of shade ranges. Choose from a well-established line rather than a seasonal one, buy your dye lots early where you can, and keep a ball band so the shade can be matched.
Warm and cool assignments are conventional, not required. Blue for cold and red for hot is the expected reading and makes the blanket legible to anyone who sees it. A monochrome palette running light to dark works just as well, and often better in a modern interior, precisely because the value ordering does the work instead of the hue.
One row a day, two, or a square
The layout determines both the finished shape and how the length behaves. A single row a day gives the classic strip and the simplest tracking. Two rows a day is how a fine gauge is made to reach a usable length, at the cost of doubling the yarn. A square a day gives portability and any shape you like, at the cost of around 365 joins.
The temperature blanket planner compares the three side by side and recalculates the size and yarn for each.
Work out the finished size before row one
Because the calendar fixes the row count, row gauge alone determines the length. This is the single most common way the project goes wrong, and it is entirely preventable.
| Row gauge | Rows per inch | 365 rows finishes | In feet |
|---|---|---|---|
| 8 rows / 4 in | 2.0 | 182.5 in | 15.2 ft |
| 12 rows / 4 in | 3.0 | 121.7 in | 10.1 ft |
| 16 rows / 4 in | 4.0 | 91.2 in | 7.6 ft |
| 24 rows / 4 in | 6.0 | 60.8 in | 5.1 ft |
A dense stitch at 24 rows per 4 in gives a manageable 60.8 in. A tall stitch at 8 rows per 4 in gives over fifteen feet. Swatch, measure your row gauge, and multiply before you commit — the gauge swatch calculator handles the measurement and the blanket size calculator gives the dimensions to aim at.
Estimating yarn when the day counts are unknowable
The total quantity is an ordinary area-and-gauge calculation, and the yarn yardage calculator handles it from your own swatch. The split between colours is the part no calculation can reach for a year in progress, because it depends on weather that has not happened yet.
So buy in two stages. Take a full quantity of any border, joining or background shade, since that amount is known from the dimensions. For the band colours, buy modestly across the range and top up as the year reveals which shades are doing the work. For a past year the problem disappears entirely: count the days per band first, then buy exactly.
Tracking 365 days without losing the thread
Record the reading, not the colour. A log of dates and numbers can rebuild the blanket after any mistake; a log of colours cannot, because the mapping is the thing you might get wrong.
Recording and crocheting do not have to happen on the same schedule. Record daily, because a missed reading is gone; crochet weekly if that suits you better. A grid laid out by month makes a gap visible the moment it appears, which a spreadsheet column of 365 rows does not.
When the data is missing
Gaps happen: a station goes offline, an archive has no reading for a date, you are away for a fortnight. Decide the rule before you start and write it down.
Three defensible rules: leave the day uncoloured and let the gap be part of the record; carry the previous day's reading forward; or take that day from the nearest station that has data, noting which. Any of them is fine as long as it is applied consistently and recorded.
What is not fine is inventing a plausible number. An invented reading is indistinguishable from a real one afterwards, which quietly turns the blanket from a record into a decoration. This is also why the planner will not fill gaps for you — it reports a day as missing and leaves it uncoloured rather than guessing.
Colour changes, and the ends nobody plans for
Here is a number that does not appear in most temperature blanket guides.
Tracking London's 2025 daily means through those six bands produces 145 colour changes, or roughly 290 ends. Tracking highs produces 114, because a warm spell holds one band for days at a time — the longest unbroken run is 27 days. Tracking lows produces 153.
Two consequences. Weave the ends in as you go, weekly, or you will finish the crochet and find a second project waiting. And if you want fewer changes, tracking highs is measurably the steadiest of the three, which is a legitimate reason to choose it.
365 or 366 days
A leap year adds one row. The Gregorian rule is that a year is a leap year if it divides by 4, except centuries, which must divide by 400 — so 2000 was a leap year and 2100 will not be. 2027 has 365 days. 2028 has 366.
If you are working squares into a grid, the day count matters more than one extra row suggests: 365 is 5 × 73, which gives an awkward grid, so most people add a border row of squares or set the odd days aside as a matching cushion.
Planning a temperature blanket for 2027
Starting on 1 January means the decisions above want making in December, not in the first week of January when you are already a few days behind.
2027 is not a leap year, so it is 365 days. A realistic December checklist: pull the last two or three years of daily data for your location and look at the actual range; set your bands from that range rather than from a chart you liked the look of; choose the palette and check it in greyscale; swatch for row gauge and calculate the finished length; then buy the background shade in full and the band colours modestly.
One further note for a January start: record from 1 January even if the yarn has not arrived. The readings are the part that cannot be recovered later; the crochet can always catch up.
Set your own bands and colours, see the year laid out, and get the finished length, stitch count and yarn estimate from your gauge.
Making a blanket for a past year
A past year is easier in every respect, and it is the version to recommend to anyone who has not done one before. The whole record exists, so you can count the days per band before buying, see the finished design in advance, adjust the bands until the balance pleases you, and work at whatever pace you like without falling behind.
It also removes the yarn problem entirely: with the day counts known, the quantity per colour is a straightforward calculation rather than a guess. A year-long project run at your own speed is a very different commitment from one with a daily deadline — the project planning guide covers keeping a long project moving.
What goes wrong, and what prevents it
| The mistake | What it costs | Decide this first |
|---|---|---|
| Copying someone else's bands | Colours that never appear, or one colour taking a third of the blanket | Look at the actual range for your location and year, then cut the bands |
| Switching between high and low partway | The record stops meaning anything and cannot be repaired | Pick one reading and write it at the top of your tracking sheet |
| Buying every colour on day one | Too much of some shades, and a discontinued dye lot for the rest | Buy the cold and mild shades first; top up as the year happens |
| Not checking the length before row 1 | A blanket over ten feet long, discovered around row 200 | Work a gauge swatch and multiply before you start |
| Recording the colour instead of the reading | One missed day and the blanket cannot be reconstructed | Log the date and the number; the colour is derived from them |
| Leaving the ends until the end | Two to three hundred ends in one sitting | Weave in as you go, at the end of each week |
Frequently asked questions
What is a crochet temperature blanket?
A temperature blanket maps each day of a year to a colour, so the finished piece is a record of that year's weather. One row or one square represents one day, the day's temperature decides which band it falls into, and the band decides the colour. A common year gives 365 rows and a leap year 366.
Should I use the high, the low or the average temperature?
Any of them, but pick one and keep it for the whole year, because switching midway makes the record meaningless. The choice changes the blanket more than most people expect. Sorting London's 2025 readings into the same six bands, the warmest band covers 109 days as daily highs and a single day as daily lows. Highs give a warmer, more settled blanket; lows a cooler one; the mean sits between and changes colour most often.
What temperature ranges should I use for a temperature blanket?
Ranges that match the year you are recording, not ranges copied from someone else's climate. Six equal-width bands across London's 2025 mean temperatures put 106 days in the busiest band and 12 in the quietest — nearly nine to one — so two colours dominate and two barely appear. Cutting the bands so each holds roughly a sixth of the year evens that out. Neither is wrong; the point is to choose deliberately.
How many colours do I need for a temperature blanket?
Most people use between five and eight. More colours give finer gradation but need more distinguishable shades, and adjacent bands that look alike in daylight will look identical in a photograph. Check the palette in greyscale: if two neighbouring colours match in lightness, the boundary between them disappears in the finished fabric.
How much yarn does a temperature blanket need?
The total comes from the finished area and your gauge, the same way as any blanket. What you cannot know in advance is the split between colours, because that depends on weather that has not happened. Buy the whole quantity of your neutral or background shade if you are using one, buy modestly across the bands, and top up as the year reveals itself.
How do I keep track of 365 days?
Record the date and the reading, not just the colour, so the blanket can be rebuilt if you lose your place. A grid with one column per month makes a missed day visible immediately, where a list of 365 numbers hides it. Batch the crochet weekly if you like, but record daily.
What do I do about missing weather data?
Decide the rule before you start and write it down. Reasonable choices are to leave the day uncoloured as part of the record, to carry the previous day forward, or to take the reading from the nearest station with data. What matters is that you apply the same rule every time and never invent a plausible number, because an invented reading is indistinguishable from a real one afterwards.
Is 2027 a leap year?
No. 2027 has 365 days, so a one-row-a-day blanket is 365 rows. The next leap year is 2028, which gives 366 rows and one extra day of whatever colour the 29th of February turns out to be.
Sources & further reading
- Open-Meteo historical weather archive — daily highs, lows and means from 1940 onwards, free for non-commercial use and no account needed. The source of every temperature on this page.
- Project planning guide — running a project that lasts a full year.
- Stripe pattern generator — for a colour sequence you design rather than one the weather dictates.
Temperature figures are real daily readings for London (51.5074, −0.1278) for the calendar year 2025, retrieved on 13 August 2026 from the Open-Meteo historical weather archive through its documented API, in degrees Celsius, with Fahrenheit equivalents converted here. All 365 days were present; none were estimated or filled. The archive publishes the temperatures; how they fall into bands, how the three readings compare and how many colour changes result are this page's own analysis. The six bands are a worked example chosen to suit this location's range, not a recommended scale — no body publishes temperature blanket bands, and one year at one place is not representative of anywhere else. Leap years follow the Gregorian rule. Palette and layout advice is practitioner convention.
Related tools
- Temperature blanket planner — bands, palette, layout, finished size and yarn from your gauge.
- Blanket size calculator — the dimensions to aim at before the calendar fixes your row count.
- Yarn yardage calculator — total yardage from your own swatch.