TechnicalGIS

Farm check

Have the rains started? What's coming in the next 10 days? Choose your farm and find out in a few seconds.

Where is the farm?

We only ask when you press this, and round it to the nearest 5 km before it leaves your phone.

Find my district

We check the middle of the district. For one farm, use your location or the map.

What you'll see

  1. Have the rains started?

    A straight yes or no, with the rain you've had in the last 30 days against what's usual.

  2. When they usually start

    The usual start date and range from 30 years of records, and how often a false start has caught farmers out.

  3. The next 10 days

    Rain and daytime heat for each day, with a plain warning for a dry spell, heavy rain or heat stress.

  4. How green it is

    Whether crops and pasture around you are greener or browner than usual for the time of year.

  5. Water for your crop

    Pick maize, sorghum, millet, beans, groundnuts or cowpeas, and see whether it needs watering in the next 10 days, and how many litres.

Advising farmers?

Farm check is made to be passed on. Each answer comes with a one-page sheet to print for a meeting or a notice board, and a short text of about 300 characters to copy into an SMS or send straight to a WhatsApp group. Both link back to the full answer.

Use it alongside your national meteorological service, which issues the official forecasts, warnings and seasonal outlooks. Every answer links to the right service for the country, and to the regional climate centre where there is one, such as ICPAC, AGRHYMET or the SADC Climate Services Centre.

Looking at a whole district? Try Season condition and the other community tools. Running a programme? Talk to us about your project.

How it works

  • Rain so far and the usual start. We read daily CHIRPS satellite rainfall for the 5 km square around your farm, back to 1991, and apply a standard rule for the start of the rains: at least 20 mm in three days, with no dry week in the month after.
  • The next 10 days. We take today's run of NOAA's Global Forecast System for your area, about 25 km across, and flag dry spells, heavy rain and hot days.
  • Greenness. We compare NASA MODIS vegetation readings for the 1 km around your farm with the same weeks in every year since 2001.

Each answer is a satellite and model estimate, so check it against what you see in the field. Answers are worked out once a day for each square, so anyone nearby gets them instantly. Read more in the Farm check guide and our mission.

Questions

What does Farm check tell me?
Four things for the spot you choose: whether the rains have started, when they usually start, the rain and heat expected over the next 10 days, and how green the crops and pasture are compared with other years. Tell us what you are growing and it adds a fifth: whether your crop needs watering, and how much.
How do you work out whether my crop needs water?
We follow the FAO method used by irrigation planners (FAO Irrigation and Drainage Paper 56). From 10 years of weather we know how fast water usually evaporates at your place at this time of year. Each crop uses a share of that which grows as the plants grow and falls as they ripen. We count the rain since planting, track how much water the soil holds, and look at the rain forecast for the next 10 days. Planting is taken as the day the rains started. One millimetre of water is one litre on every square metre.
How do you decide the rains have started?
We use a standard farming rule: the first time after the usual start of the season that at least 20 mm falls within three days, with no dry spell of seven days or more in the 30 days that follow (after Stern and others, 1981, and Sivakumar, 1988). Rain followed by a long dry spell counts as a false start.
Where does the forecast come from?
From NOAA's Global Forecast System, updated every day. For official forecasts and warnings, check your national meteorological service: every answer links to it.
I advise farmers. How do I pass the answer on?
Every answer has a one-page sheet you can print for a meeting or notice board, and a short text of about 300 characters you can copy into an SMS or send straight to a WhatsApp group. Each carries a link back to the full answer.
Do you keep my location?
We only ask for your location when you press "Use my location", and we round it to the nearest 5 km square before it leaves your phone. Answers are kept for 7 days so anyone in the same square gets them instantly.
Does it work everywhere?
It works for any place between 60°S and 60°N, and is built for farms that depend on a rainy season, especially in Africa, South Asia and Latin America. Where there are two rainy seasons, it watches the one that is due next.

Data and credits

You're welcome to use the answers in reports and talks. Keep the line "Generated at TechnicalGIS.com" and the data credits. Privacy.