Gardening in Uruguay: climate, frost dates and crops by region

We worked out the season of 10 cities of Uruguay from ten years of weather: the frost-free season lasts from 315 days in Rivera to 347 days in Paysandú. The last spring frost comes first in Colonia del Sacramento (around 9 July) and last in Rivera (around 30 July). One of the cities had no frost at all.

Climate zones of Uruguay

By the days between the last spring frost and the first autumn frost.

Zone	Cities	Frost-free days	Last spring frost	First autumn frost
270 frost-free days or more	Rivera, Tacuarembó, Paysandú, Melo, Mercedes	315 – 347	13 July – 30 July	10 June – 27 June
Frost without a regular season	Salto, Colonia del Sacramento, Las Piedras, Maldonado	—	9 July – 15 July	—
No frost in ten years	Montevideo	—	—	—

How the regions of Uruguay differ

Splitting the cities in two — north (Rivera, Salto, Tacuarembó and 2 more) and south (Mercedes, Colonia del Sacramento, Las Piedras and 2 more): the north gets about 1,385 mm of rain a year and the south about 1,082 mm.

The gap between the warmest month’s days and the coldest month’s nights is widest in Mercedes (23.3 °C) and smallest in Maldonado (17.5 °C): the smaller it is, the milder both winter and summer. Rivera is the wettest of these cities with 1,436 mm a year, Montevideo the driest with 981 mm. The hottest summer days are in Salto (31.1 °C on average in the warmest month), the coolest in Maldonado (26.2 °C). In none of these cities does a month average below 0 °C at night.

Which crops suit which part of Uruguay

Season long enough: the days from planting to the first autumn frost cover the days to the first harvest on the plant card. Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

Crop	Planting out or sowing	Season long enough	Tight or too short
Tomato	27 July (Paysandú) – 6 March (Paysandú)	all 9	—
Cucumber	21 September (Paysandú) – 11 April (Paysandú)	all 9	—
Bell Pepper, Eggplant	21 September (Paysandú) – 6 March (Paysandú)	all 9	—
Zucchini	21 September (Paysandú) – 9 April (Paysandú)	all 9	—
Pumpkin	21 September (Paysandú) – 1 March (Paysandú)	all 9	—
Watermelon	21 September (Paysandú) – 17 March (Paysandú)	all 9	—
Peas	22 June (Melo) – 2 April (Mercedes)	8 of 9: Rivera, Salto, Tacuarembó, Melo and 4 more	1 of 9: Paysandú
Garlic	Autumn planting: 16 April (Rivera) – end of June (Rivera)	—	—
Tulip, Daffodil, Crocus, Hyacinth	Autumn planting: by 11 May (Rivera)	—	—

Cities without a spring frost: months that suit each crop

Months whose average day is not above the highest temperature on the plant card and whose average night is not below its lowest.

City	Tomato	Cucumber	Bell Pepper	Eggplant	Watermelon
Montevideo	November–April	December–March	November–April	none	December–March

Cities of Uruguay: weather in numbers

City	Frost-free days	Warmest month, day	Coldest month, night	Rain a year	Driest month	Places to buy
Rivera	315	January, 29.6 °C	July, 8.1 °C	1,436 mm	June	2
Salto	—	January, 31.1 °C	July, 8.8 °C	1,290 mm	July	6
Tacuarembó	328	January, 29.5 °C	July, 7.5 °C	1,385 mm	June	1
Paysandú	347	January, 30.8 °C	July, 8 °C	1,232 mm	June	1
Melo	336	January, 28.8 °C	July, 7.8 °C	1,404 mm	November	—
Mercedes	337	January, 30.8 °C	July, 7.5 °C	1,089 mm	June	—
Colonia del Sacramento	—	January, 28.9 °C	July, 8 °C	1,082 mm	June	2
Las Piedras	—	January, 28.8 °C	July, 7.3 °C	1,023 mm	September	—
Montevideo	no frost	January, 26.5 °C	July, 8.9 °C	981 mm	September	29
Maldonado	—	January, 26.2 °C	July, 8.7 °C	1,088 mm	September	24

ERA5 2016–2025 via Open-Meteo, 25 km grid cell of each city; dates by the Greenly calendar and the plant cards.