In San Jerónimo Zacualpan, the wet season is overcast, the dry season is partly cloudy, and it is comfortable year round. Over the course of the year, the temperature typically varies from 42°F to 78°F and is rarely below 36°F or above 84°F.
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Based on the tourism score, the best time of year to visit San Jerónimo Zacualpan for warm-weather activities is from late March to late May.
The warm season lasts for 2.4 months, from March 27 to June 8, with an average daily high temperature above 76°F. The hottest day of the year is May 4, with an average high of 78°F and low of 52°F.
The cool season lasts for 2.1 months, from December 1 to February 5, with an average daily high temperature below 70°F. The coldest day of the year is January 12, with an average low of 42°F and high of 69°F.
Average High and Low Temperature
The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.
In San Jerónimo Zacualpan, 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 Jerónimo Zacualpan begins around October 30 and lasts for 6.8 months, ending around May 23. On February 25, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy70% of the time, and overcast or mostly cloudy30% of the time.
The cloudier part of the year begins around May 23 and lasts for 5.2 months, ending around October 30. On September 15, the cloudiest day of the year, the sky is overcast or mostly cloudy88% of the time, and clear, mostly clear, or partly cloudy12% of the time.
Cloud Cover Categories
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in San Jerónimo Zacualpan varies very significantly throughout the year.
The wetter season lasts 4.6 months, from May 23 to October 12, with a greater than 40% chance of a given day being a wet day. The chance of a wet day peaks at 76% on June 27.
The drier season lasts 7.4 months, from October 12 to May 23. The smallest chance of a wet day is 3% on December 8.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 76% on June 27.
Daily Chance of Precipitation
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).
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 Jerónimo Zacualpan experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 7.5 months, from April 3 to November 18, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around June 30, with an average total accumulation of 5.7 inches.
The rainless period of the year lasts for 4.5 months, from November 18 to April 3. The least rain falls around December 17, with an average total accumulation of 0.2 inches.
Average Monthly Rainfall
The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.
The length of the day in San Jerónimo Zacualpan varies over the course of the year. In 2018, the shortest day is December 21, with 10 hours, 58 minutes of daylight; the longest day is June 21, with 13 hours, 18 minutes of daylight.
Hours of Daylight and Twilight
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.
The earliest sunrise is at 6:27 AM on March 31, and the latest sunrise is 1 hour, 4 minutes later at 7:31 AM on October 27. The earliest sunset is at 5:53 PM on November 25, and the latest sunset is 2 hours, 22 minutes later at 8:15 PM on July 5.
Daylight saving time (DST) is observed in San Jerónimo Zacualpan during 2018, starting in the spring on April 1, lasting 6.8 months, and ending in the fall on October 28.
Sunrise & Sunset with Twilight and Daylight Saving Time
The solar day over the course of the year 2018. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.
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 Jerónimo Zacualpan, 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.
Humidity Comfort Levels
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.
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 Jerónimo Zacualpan experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 3.7 months, from December 29 to April 21, with average wind speeds of more than 5.5 miles per hour. The windiest day of the year is March 8, with an average hourly wind speed of 6.3 miles per hour.
The calmer time of year lasts for 8.3 months, from April 21 to December 29. The calmest day of the year is May 20, with an average hourly wind speed of 4.7 miles per hour.
Average Wind Speed
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.
The predominant average hourly wind direction in San Jerónimo Zacualpan varies throughout the year.
The wind is most often from the east for 4.0 months, from May 28 to September 28, with a peak percentage of 68% on July 25. The wind is most often from the north for 2.3 months, from September 28 to December 6, with a peak percentage of 44% on October 11. The wind is most often from the south for 5.7 months, from December 6 to May 28, with a peak percentage of 33% on January 1.
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).
Best Time of Year to Visit
To characterize how pleasant the weather is in San Jerónimo Zacualpan 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 Jerónimo Zacualpan for general outdoor tourist activities is from late March to late May, with a peak score in the last week of April.
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
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 Jerónimo Zacualpan for hot-weather activities is from late March to late May, with a peak score in the last week of April.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
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).
While it does not do so every year, freezing temperatures are seen in San Jerónimo Zacualpan over some winters. The day least likely to be in the growing season is January 5, with a 70% chance.
Time Spent in Various Temperature Bands and the Growing Season
The percentage of time spent in various temperature bands: frigid < 15°F < freezing < 32°F < very cold < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The black line is the percentage chance that a given day is within the growing season.
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 Jerónimo Zacualpan should appear around January 16, only rarely appearing before January 13 or after January 19.
Growing Degree Days
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.
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 2.7 months, from March 6 to May 27, with an average daily incident shortwave energy per square meter above 6.8 kWh. The brightest day of the year is April 18, with an average of 7.3 kWh.
The darker period of the year lasts for 2.4 months, from November 10 to January 23, with an average daily incident shortwave energy per square meter below 5.5 kWh. The darkest day of the year is December 22, with an average of 5.1 kWh.
Average Daily Incident Shortwave Solar Energy
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.
For the purposes of this report, the geographical coordinates of San Jerónimo Zacualpan are 19.241 deg latitude, -98.261 deg longitude, and 7,346 ft elevation.
The topography within 2 miles of San Jerónimo Zacualpan contains significant variations in elevation, with a maximum elevation change of 614 feet and an average elevation above sea level of 7,365 feet. Within 10 miles contains significant variations in elevation (2,329 feet). Within 50 miles contains large variations in elevation (14,183 feet).
The area within 2 miles of San Jerónimo Zacualpan is covered by cropland (86%), within 10 miles by cropland (76%) and shrubs (13%), and within 50 miles by cropland (47%) and trees (20%).
This report illustrates the typical weather in San Jerónimo Zacualpan, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in San Jerónimo Zacualpan.
The estimated value at San Jerónimo Zacualpan is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between San Jerónimo Zacualpan and a given station.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.