Climate and Average Weather Year Round in San Isidro Mexico

In San Isidro, the wet season is comfortable and overcast and the dry season is cool and partly cloudy. Over the course of the year, the temperature typically varies from 40°F to 72°F and is rarely below 34°F or above 78°F.

Based on the tourism score, the best time of year to visit San Isidro for warm-weather activities is from early April to late May.

The warm season lasts for 2.3 months, from April 3 to June 14, with an average daily high temperature above 69°F. The hottest month of the year in San Isidro is May, with an average high of 71°F and low of 51°F.

The cool season lasts for 2.4 months, from November 27 to February 9, with an average daily high temperature below 62°F. The coldest month of the year in San Isidro is January, with an average low of 40°F and high of 61°F.

In San Isidro, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.

The clearer part of the year in San Isidro begins around October 26 and lasts for 7.2 months, ending around June 2.

The clearest month of the year in San Isidro is March, during which on average the sky is clear, mostly clear, or partly cloudy 65% of the time.

The cloudier part of the year begins around June 2 and lasts for 4.7 months, ending around October 26.

The cloudiest month of the year in San Isidro is September, during which on average the sky is overcast or mostly cloudy 83% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in San Isidro varies very significantly throughout the year.

The wetter season lasts 4.6 months, from May 26 to October 14, with a greater than 49% chance of a given day being a wet day. The month with the most wet days in San Isidro is August, with an average of 24.9 days with at least 0.04 inches of precipitation.

The drier season lasts 7.4 months, from October 14 to May 26. The month with the fewest wet days in San Isidro is January, with an average of 4.9 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in San Isidro is August, with an average of 24.9 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 83% on August 31.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. San Isidro experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year in San Isidro. The month with the most rain in San Isidro is September, with an average rainfall of 9.2 inches.

The month with the least rain in San Isidro is January, with an average rainfall of 0.8 inches.

The length of the day in San Isidro varies over the course of the year. In 2024, the shortest day is December 21, with 10 hours, 56 minutes of daylight; the longest day is June 20, with 13 hours, 20 minutes of daylight.

The earliest sunrise is at 5:49 AM on June 5, and the latest sunrise is 1 hour, 17 minutes later at 7:07 AM on January 18. The earliest sunset is at 5:48 PM on November 25, and the latest sunset is 1 hour, 24 minutes later at 7:12 PM on July 4.

Daylight saving time (DST) is not observed in San Isidro during 2024.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in San Isidro, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in San Isidro experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.4 months, from February 16 to August 27, with average wind speeds of more than 5.3 miles per hour. The windiest month of the year in San Isidro is April, with an average hourly wind speed of 5.9 miles per hour.

The calmer time of year lasts for 5.6 months, from August 27 to February 16. The calmest month of the year in San Isidro is December, with an average hourly wind speed of 4.7 miles per hour.

The predominant average hourly wind direction in San Isidro varies throughout the year.

The wind is most often from the east for 8.4 months, from January 9 to September 21 and for 1.0 months, from November 25 to December 26, with a peak percentage of 62% on July 6. The wind is most often from the north for 2.1 months, from September 21 to November 25 and for 2.0 weeks, from December 26 to January 9, with a peak percentage of 42% on October 7.

San Isidro is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 4.3 months, from June 9 to October 17, with an average temperature above 82°F. The month of the year in San Isidro with the warmest water is August, with an average temperature of 85°F.

The time of year with cooler water lasts for 3.2 months, from December 22 to March 29, with an average temperature below 75°F. The month of the year in San Isidro with the coolest water is February, with an average temperature of 73°F.

To characterize how pleasant the weather is in San Isidro throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit San Isidro for general outdoor tourist activities is from early April to late May, with a peak score in the second week of May.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit San Isidro for hot-weather activities is from mid April to late May, with a peak score in the second week of May.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in San Isidro typically lasts for 10 months (313 days), from around February 11 to around December 20, rarely starting after March 18, or ending before November 5.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in San Isidro should appear around February 1, only rarely appearing before January 25 or after February 8.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 3.0 months, from March 13 to June 14, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest month of the year in San Isidro is May, with an average of 6.9 kWh.

The darker period of the year lasts for 2.5 months, from November 11 to January 27, with an average daily incident shortwave energy per square meter below 5.0 kWh. The darkest month of the year in San Isidro is December, with an average of 4.6 kWh.

For the purposes of this report, the geographical coordinates of San Isidro are 19.796 deg latitude, -97.384 deg longitude, and 6,916 ft elevation.

The topography within 2 miles of San Isidro contains large variations in elevation, with a maximum elevation change of 2,100 feet and an average elevation above sea level of 7,123 feet. Within 10 miles contains large variations in elevation (7,995 feet). Within 50 miles also contains extreme variations in elevation (13,704 feet).

The area within 2 miles of San Isidro is covered by cropland (42%), shrubs (30%), and trees (24%), within 10 miles by trees (41%) and cropland (35%), and within 50 miles by cropland (61%) and trees (23%).