Frost dates for Tehran, Iran
Half of years have their last spring frost by April 16, but 1 year in 10 still frosts after April 30.
A frost date is really a percentile, here from 30 years (1991 to 2020) of a weather model’s daily lows near Tehran: in about half of years a frost still comes after the median date. Both numbers are below, so you can choose the risk yourself.
The odds
Last spring frost
How often a frost still comes on or after each date.
- 1 year in 10
- April 30
- 1 year in 5
- April 26
- 3 years in 10
- April 23
- 2 years in 5
- April 19
- Half of years (the median)
- April 16
First fall freeze
How often the first freeze comes on or before each date.
- 1 year in 10
- October 31
- 1 year in 5
- November 2
- 3 years in 10
- November 4
- 2 years in 5
- November 7
- Half of years (the median)
- November 8
- Growing season
- about 204 days
- Hardiness zone nearby
- 6b, estimated from the weather model
Where these numbers come from
Modeled, not measured. No weather station stands behind these dates. They come from ERA5, a reconstruction of the world’s weather from 1991 to 2020 made by ECMWF, Europe’s medium-range weather forecasting agency, for the EU’s Copernicus program, and read here through Open-Meteo. They are the model’s daily lows for the point at 35.75, 51.25, 18 km (11 miles) from the center of Tehran. A frost here means a low at or below 0 °C (32 °F).
A weather model sees the land in squares about 25 km (16 miles) across, so it can miss what sets one garden apart from the next: a frost hollow, a hillside, a lakeshore, a city’s own warmth. The Milpa planner reads these same numbers for a garden here and grades them A good hunch.
Cold air also pools in low ground on the clear, still nights when frost happens, so a hollow can freeze while a slope a hundred meters away does not. No table can know that about your garden. Your own logged frosts eventually can.
Weather data by Open-Meteo.com, under CC BY 4.0. Contains modified Copernicus Climate Change Service information, 2026.
What can I plant here, and when? ›
Nearby cities
The nearest cities with a frost page here, and how their last-frost dates compare.
- Karaj, Iran, last frost by March 29
- Isfahan, Iran, last frost by March 21
- Tabriz, Iran, last frost by April 18
- Baku, Azerbaijan, frost is rare
- Shiraz, Iran, last frost by March 9
- Baghdad, Iraq, frost is rare
Other cities in Iran.
- Mashhad, Iran, last frost by March 22