Frost dates in Johannesburg: last spring frost and first autumn frost
When is it safe to plant out in Johannesburg, and when does the first frost come? Dates from 45 years of nightly minimum temperatures (1981–2025), with how early or late they can fall.
Frost dates in Johannesburg and how sure they are
| Early year (1 in 10) | Typical (median) | Late year (1 in 10) | |
|---|---|---|---|
| Last spring frost | 6 August | 22 August | 10 September |
| First autumn frost | 6 May | 4 June | 18 June |
In a typical year the last frost in Johannesburg falls around 22 August and the first one around 4 June, leaving about 284 frost-free days (between 253 and 351 in 8 years out of 10). To be safe, plant tender crops after 10 September: by then the last frost has passed in 9 years out of 10. Bring them in before 6 May: in 1 year in 10 the first frost comes earlier.
Southern hemisphere: the frost season is the austral winter, so the last spring frost comes around August–October and the first autumn frost around April–June.
In 5 of the 45 years Johannesburg had no spring frost at all; those years are left out of the spring dates.
Frost month by month in Johannesburg
| Month | Average low | Coldest night (avg) | Record low | Frost nights | Years with frost |
|---|---|---|---|---|---|
| January | 13.8 °C | 10 °C | 5.6 °C | 0 | 0% |
| February | 13.5 °C | 9.9 °C | 7.4 °C | 0 | 0% |
| March | 12.1 °C | 7.9 °C | 4.7 °C | 0 | 0% |
| April | 8.8 °C | 3.7 °C | -0.8 °C | 0.1 | 9% |
| May | 5.1 °C | 0.3 °C | -5.6 °C | 1.2 | 36% |
| June | 2 °C | -2.4 °C | -6.2 °C | 6 | 93% |
| July | 1.5 °C | -3 °C | -6.7 °C | 7.7 | 98% |
| August | 4 °C | -1.3 °C | -5.6 °C | 2.5 | 80% |
| September | 7.7 °C | 2.1 °C | -3.2 °C | 0.5 | 27% |
| October | 10.3 °C | 4.9 °C | 1.1 °C | 0 | 0% |
| November | 11.9 °C | 6.6 °C | 2.9 °C | 0 | 0% |
| December | 13.4 °C | 9 °C | 2.7 °C | 0 | 0% |
Frost here means a night minimum at or below 0 °C at 2 m. Frost nights is the average count per month; years with frost is how many years had at least one.
Frost alerts for your garden or field
LayEarth Business Agro sends an alert when the forecast low at your saved site drops below your threshold (0 °C by default), with frost risk, hours below zero and white or black frost for each forecast day. LayEarth Pro, from 9 USD a month, adds alerts for the places you follow.
Temperature map around Johannesburg
The live temperature layer of the map (NOAA GFS forecast): watch the cold nights coming hour by hour.
More for Johannesburg
Weather in Johannesburg now · Will it rain today in Johannesburg? · Open the temperature map on Johannesburg
Questions
- When is the last frost in Johannesburg?
- On average around 22 August. In an early year the last frost comes by 6 August, in a late one (1 year in 10) after 10 September.
- When is the first frost in Johannesburg?
- On average around 4 June. In 1 year in 10 it comes before 6 May, in a mild year not until 18 June.
- How long is the growing season in Johannesburg?
- About 284 frost-free days between the last spring frost and the first autumn frost, from 253 in a short year to 351 in a long one.
- When can I plant tomatoes in Johannesburg?
- Frost-tender plants such as tomatoes, peppers, beans and courgettes go out after the last frost: after 10 September the risk is down to 1 year in 10. Hardy crops can go earlier.
- How cold does it get in Johannesburg?
- The coldest night of winter averages -3.9 °C; the lowest since 1981 was -6.7 °C in 2000.
Frost dates nearby
How these dates are computed
Daily minimum temperature at 2 m from NASA POWER (MERRA-2 reanalysis, public domain), 1981–2025, corrected from the ~50 km grid to the real altitude of Johannesburg (6.5 °C per km). For each year: the last night at or below 0 °C before midsummer and the first one after it; the dates are the median and the 10% / 90% of those years. A garden in a frost pocket or a city centre can differ by days. Live temperatures: the temperature layer of the map.