The short answer: September. The water is still warm, the beach stays open until mid-month, and the queues in Monsaraz have gone.
The longer answer depends on why you're coming — because Alqueva in January and Alqueva in August are effectively different places.
The numbers, month by month
Real averages for Mourão, calculated over ten years of observations (2015–2024):
| Month | High | Low | Rain | Days above 35°C |
|---|---|---|---|---|
| January | 15° | 5° | 44 mm | 0 |
| February | 17° | 6° | 43 mm | 0 |
| March | 19° | 8° | 70 mm | 0 |
| April | 22° | 10° | 60 mm | 0 |
| May | 26° | 13° | 29 mm | 1 |
| June | 30° | 16° | 12 mm | 6 |
| July | 35° | 19° | 2 mm | 15 |
| August | 35° | 19° | 1 mm | 14 |
| September | 30° | 17° | 27 mm | 3 |
| October | 25° | 14° | 75 mm | 0 |
| November | 19° | 9° | 60 mm | 0 |
| December | 16° | 7° | 54 mm | 0 |
Look at July and August: the average high is 35°C, and there are fifteen days a month above that. It isn't an occasional spike, it's the whole month. And July gets 2 mm of rain — essentially none.
July and August
This is when most people come, and it makes sense: the lake is warm, the river beach is open and lifeguarded, and it doesn't rain.
But here's what first-time visitors don't expect: between two and five in the afternoon, nothing happens outdoors. It isn't discomfort, it's impractical. The day organises itself around that — morning in the water, afternoon in the shade or the pool, evening out walking.
Which is why a pool where you're staying stops being an extra and becomes the thing that saves your afternoons. Where to stay on Alqueva →
September — the sweet spot
The lake has held the summer's heat and stays comfortable. Highs drop to 30°C, with only three days above 35 in the whole month. The river beach usually stays open until mid-September.
And Monsaraz becomes visitable at any hour again, without the coach parties that fill it in August.
One caveat: the second half of the month starts to bring rain.
May and June
Probably the most beautiful season. In May the plain is still green, which in the Alentejo doesn't last — from June it turns gold and stays that way until the October rains.
Temperatures are pleasant (26°C in May, 30°C in June) and there's little rain. What's missing is the water: the lake is still cold in May, and the bathing season only starts around mid-June.
Good for anyone coming for Monsaraz, walking and wineries — less so for swimming.
October to April
Cold at night, short days, and this is when it rains — October is the wettest month, at 75 mm. Many restaurants cut their hours and some serve only lunch.
In exchange:
It's the best season for stars. Much longer nights and cleaner air. Since Alqueva is a Dark Sky reserve, that matters — if you're coming for the sky, come in winter, not summer.
There's nobody here. Monsaraz in February is a completely different experience from Monsaraz in August.
It's cheaper. There isn't much accommodation in the region and prices follow the season.
Summary
| If you're coming for… | Come in… |
|---|---|
| Swimming and the beach | July to mid-September |
| Green landscape | April and May |
| Overall balance | September |
| Stars | October to March, at new moon |
| Quiet and low prices | November to February |
| The grape harvest | Late August and September |
One last thing: our homepage shows the real temperature in Mourão right now, and how good tonight's sky is for stars. If you're choosing dates, it's a good place to start.
