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San Juan in May: Weather, Average temperature and Climate

Planning a trip and want to know what the weather in San Juan in May will be like? Take a look at our weather guide for San Juan, based on historical data.
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May

Weather in San Juan in May 2025

OK Weather
Warm
🌧️
Rainy
🌊
Warm water
If you plan to visit San Juan in May, the weather is typically alright, with an average high temperature of +86°F during the day and approximately 1 sunny days. Expect some rainy, though, as there are typically 22 rainy days in the month and around 146 mm of precipitation. The weather is changeable so you may have to pack for every eventuality. Search flights in one click on Avionero.

Average weather

☀️
+86°F
Avg. max. temperature
+46°F
Min.
+91°F
Max.
146 mm
Total precipitation
77%
Avg. humidity
3 m/s
Avg. wind
1 ☀️
Sunny Days
4 ⛅️
Cloudy
22 🌦
Rainy
Our opinion: San Juan has OK weather in May.

Average temperature in San Juan in May

Here are the expected maximum, average and minimum temperatures in San Juan for May based on the historical data.
Last Year
Historical Data

The expected average maximum temperature in May is +90°F with a maximum of +91°F and a minimum of +73°F.

The average maximum temperature goes up 0% by the end of the month, compared with the beginning of the month, from +91°F to +91°F.

Is San Juan warm or cold in May?

San Juan is typically warm in May.

Maximum temperatures go up compared to the previous month from +84°F to +86°F. The minimum temperature also goes up from +73°F to +75°F.

It’s generally warm, but pack a long-sleeve shirt for evenings.

Take a look at how May is compared to other months in San Juan:

Water temperature in San Juan in May

Water in San Juan in May is Warm. It varies from +80°F to +82°F, with an average of +81°F. This is almost similar to the air temperature, which averages +86°F.

In May, water temperatures are average relative to the rest of the year:

The warmest water temperatures in San Juan are reached in September, when the average sea temperature rises to +85°F. The coldest water temperatures are in February, with an average of +79°F.

Can you swim in San Juan in May?

You can absolutely swim in San Juan in May, the water is warm (+81°F in average), similar to heated pools. Suitable for most people, including children and the elderly.
🦭
Cold
Below +61°F
🏄‍♂️
Fresh
61°F - 70°F
🏊
Comfortable
70°F - 77°F
👙
Warm
77°F - 82°F
🔥
Very warm
+82°C and up
Bring your swimming suit, sunscreen and your favorite inflatable pink flamingo.

Climate in San Juan in May

San Juan weather looks like this, on average, in May and the surrounding months.
AprilMayJune
Avg. temperature
+84°F+86°F+88°F
Min. temperature
+70°F+46°F+72°F
Max. temperature
+91°F+91°F+95°F
Rainfall
94 mm146 mm79 mm
Wind
3 m/s3 m/s3 m/s
Avg. water temperature
+80°F+81°F+83°F
Humidity
74%77%77%
Air pressure
1015 HPa1015 HPa1016 HPa
Sunny days
212
Cloudy days
545
Rainy days
232220
Snowy days
000

May typically has worse weather conditions compared to April. It’s getting warmer as May arrives. The average maximum temperature goes up from +84°F to +86°F during the day. Prepare for more rain. Average rainfall goes from 94 mm to 146 mm. Humidity rises from 74% to 77%. The average wind speed doesn’t change much during May, staying around 3 m/s. The days becoming less sunny, going from 2 sunny days in April to 1 in May.

June brings much the same weather, it remains ok.

Wind

Wind speed in San Juan in May based on historical data.
Last Year
Historical Data

The average wind speed is 3 m/s getting up to 5 m/s which is a light breeze; barely moving the tree leaves.

The average wind speed in San Juan is gradually increasing during May, going from 3 m/s to 3 m/s over the course of the month.

Rain

Amount of rainfall in mm during May in San Juan based on historical data.
Last Year
Historical Data
Typically, there is a 58% chance of rain on an average day in May, with total rainfall of approximately 123 mm. The maximum amount of rainfall per day is around 32 mm, which is moderate rain. May is a pretty wet month with over 18 rainy days, so don’t forget to pack an umbrella, raincoat, and a pair of wellies.
May is one of the rainiest months in San Juan, here is a comparison with other months, total mm:
San Juan wettest month is October, where a typical day has a 68% chance of precipitation and 151 mm of rainfall per day. January, on the other hand, is the driest month with a mere 68% chance of precipitation and 38 mm of rainfall per day.

How was the weather last May in San Juan?

This is the weather in San Juan in May 2023:
1 May
☁️
+91°F
2 May
☀️
+88°F
3 May
☁️
+91°F
4 May
☁️
+90°F
5 May
☁️
+89°F
6 May
🌫️
+91°F
7 May
🌫️
+89°F
8 May
🌫️
+90°F
9 May
🌫️
+92°F
10 May
🌫️
+91°F
11 May
☀️
+91°F
12 May
☁️
+87°F
13 May
🌧️
+86°F
14 May
🌧️
+87°F
15 May
🌫️
+90°F
16 May
☀️
+90°F
17 May
☁️
+89°F
18 May
☁️
+90°F
19 May
☀️
+85°F
20 May
🌧️
+88°F
21 May
🌧️
+87°F
22 May
🌧️
+88°F
23 May
☁️
+88°F
24 May
🌧️
+90°F
25 May
☁️
+91°F
26 May
☁️
+90°F
27 May
☀️
+91°F
28 May
☁️
+88°F
29 May
☁️
+88°F
30 May
☀️
+84°F
31 May
☁️
+91°F
In May 2023 San Juan had 6 sunny days, 13 cloudy days, and 6 rainy days. The average maximum temperature was +90°F, with an absolute maximum of +91°F and a minimum of +84°F. The average humidity was 80%, with a maximum of 100% and a minimum of 57%. The average wind speed was 3 m/s, with a maximum of 10 m/s and a minimum of 0 m/s.
Are you planning a trip in May?

Climate Change Over the Years

This is how San Juan climate has changed over the last 43 years.

The climate in San Juan in May has not changed that much over the last 43 years.

The average temperature was the lowest in 2008 (+84°F) and the highest in 2013 (+87°F). The driest year was 1994 with only 675 mm of rainfall, and the wettest year was 2023 with 2338 mm.

FAQ

Frequently asked questions about the weather in San Juan in May:

Is May a good time to visit San Juan?

It’s always a good time to visit San Juan, but the weather is changeable in May, so plan a mix of indoor and outdoor activities and exploring, and pack for every eventuality.

Can you sunbathe in San Juan in May?

May is warm in San Juan. You may enjoy some beach or pool time in the day, but pack something a tad warmer for the evening.

Can you swim in San Juan in May?

Yes, you can swim in San Juan in May, the water temperature averaging at +81°F. This temperature is considered warm and comfortable for most swimmers.

Is San Juan rainy in May?

San Juan is often rainy in May. You may get a bit damp when outside, so pack an umbrella, and maybe even a raincoat.

Is it sunny in San Juan in May?

Usually, it’s not very sunny in San Juan in May, often it’s pretty cloudy. Pack for any eventuality; layering can help reduce the number of bulky items needed.

Monthly weather in San Juan

Source of the data

For this page, we’ve looked at the typical weather in San Juan, based on historical hourly weather data from January 1, 1979, to December 31, 2022.

For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.