The climate of Modesto can be defined as Mediterranean, given that the winters are mild and rainy, and the summers are hot and sunny. However, there are some differences in comparison with the typical Mediterranean climate: in winter, fog can form at night and in the early morning; in summer, there are strong diurnal temperature variations, so it is quite cool at night and hot during the day; the rainy period is shorter, so in autumn, in September and October, it still rains rarely.
The city is located in the northern part of San Joaquin valley. Here, the difference in temperature between night and day and between winter and summer are much larger than in San Francisco, which is located 125 km (75 mi) to the north-west.
On the coldest days of the year, the temperature generally drops to -1/-3 °C (27/30 °F) at night, while it reaches about 10 °C (50 °F) during the day. But in December 1990, it reached -7 °C (19.5 °F). Snow is extremely rare: in practice, it never snows. On the days when there is no fog and no rain, the temperature can reach 18/19 °C (64/66 °F) even in the middle of winter.
On the hottest days of the year, the temperature can reach 40/42 °C (104/108 °F). In August 2017, it reached 43 °C (109.5 °F), and in July 2006, even 45 °C (113 °F). It can sometimes be very hot even in late April and early October. However, since the daytime temperature range is very strong, generally, at night it gets quite cool even in the height of summer.
The average temperature of the coldest month (December) is of 8.6 °C (47.5 °F), that of the warmest month (July) is of 26 °C (78.9 °F). Here are the average temperatures.
| Month | Min (°C) | Max (°C) | Mean (°C) | Min (°F) | Max (°F) | Mean (°F) |
|---|---|---|---|---|---|---|
| January | 3.8 | 13.4 | 8.6 | 39 | 56 | 47.5 |
| February | 5.4 | 16.8 | 11.1 | 42 | 62 | 52 |
| March | 7.3 | 20.1 | 13.7 | 45 | 68 | 56.7 |
| April | 9.1 | 23.2 | 16.2 | 48 | 74 | 61.1 |
| May | 12.1 | 27.8 | 19.9 | 54 | 82 | 67.9 |
| June | 15.1 | 32.1 | 23.6 | 59 | 90 | 74.5 |
| July | 17.1 | 35 | 26 | 63 | 95 | 78.9 |
| August | 16.7 | 34.2 | 25.4 | 62 | 94 | 77.8 |
| September | 14.8 | 31.7 | 23.2 | 59 | 89 | 73.8 |
| October | 10.8 | 26.1 | 18.5 | 51 | 79 | 65.2 |
| November | 6.2 | 18.7 | 12.5 | 43 | 66 | 54.4 |
| December | 3.7 | 13.4 | 8.6 | 39 | 56 | 47.4 |
| Year | 10.2 | 24.4 | 17.25 | 50.4 | 75.9 | 63 |
Precipitation amounts to 310 millimeters (12.2 inches) per year: it is therefore scarce (although in winter there may be periods of bad weather). It ranges from 0 mm (0 in) in the driest months (July, August, September) to 65 mm (2.6 in) in the wettest (January). Here is the average precipitation.
| Month | Millimeters | Inches | Days |
|---|---|---|---|
| January | 65 | 2.6 | 10 |
| February | 55 | 2.2 | 9 |
| March | 45 | 1.8 | 8 |
| April | 25 | 1 | 5 |
| May | 15 | 0.6 | 3 |
| June | 5 | 0.2 | 1 |
| July | 0 | 0 | 0 |
| August | 0 | 0 | 0 |
| September | 0 | 0 | 0 |
| October | 15 | 0.6 | 2 |
| November | 25 | 1 | 6 |
| December | 55 | 2.2 | 9 |
| Year | 310 | 12.2 | 53 |
Best Time
The best times to visit Modesto are spring and autumn, to avoid the night-time cold, the fog and the rain of winter, as well as the summer heat. In particular, you can choose the months of April and October, bearing in mind that it is necessary to dress in layers because there are strong temperature differences between night and day.
Back to California.
Modesto - Weather by month
Based on the period 1991-2020
(January - February - March - April - May - June - July - August - September - October - November - December)
January is generally a mild month. The average temperature is of 8.6 °C (47 °F), with a minimum of 3.8 °C (38.8 °F) and a maximum of 13.4 °C (56.1 °F). 
On the coldest nights of the month, the temperature usually drops to around -1.5 °C (29.5 °F). However, it dropped to -5 °C (23 °F) in January 2007.
On the warmest days of the month, the temperature usually reaches around 19 °C (66 °F). However, it reached 22.8 °C (73 °F) in January 2014.
Precipitation amounts to 65 mm (2.6 in), distributed over 10 days.
The day lasts on average 9 hours and 55 minutes.
The average humidity is 80%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).
February is generally a mild month. The average temperature is of 11.1 °C (52 °F), with a minimum of 5.4 °C (41.8 °F) and a maximum of 16.8 °C (62.2 °F). On the coldest nights of the month, the temperature usually drops to around 0.5 °C (32.5 °F). However, it dropped to -2.8 °C (27 °F) in February 2018.On the warmest days of the month, the temperature usually reaches around 22 °C (71.5 °F). However, it reached 26.7 °C (80.1 °F) in February 2020.Precipitation amounts to 55 mm (2.2 in), distributed over 9 days.
The day lasts on average 10 hours and 50 minutes.
The average humidity is 70%.
The average wind speed is 9 kph (6 mph).
March is generally a mild month. The average temperature is of 13.7 °C (57 °F), with a minimum of 7.3 °C (45.2 °F) and a maximum of 20.1 °C (68.1 °F). On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 2.5 °C (36.5 °F). However, it dropped to 0.1 °C (32.2 °F) in March 1998.On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 26.5 °C (80 °F). However, it reached 30.6 °C (87.1 °F) in March 2015.Precipitation amounts to 45 mm (1.8 in), distributed over 8 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 62%.
The average wind speed is 10 kph (6 mph).
April is generally a very mild month. However, there are remarkable differences between night and day. The average temperature is of 16.2 °C (61 °F), with a minimum of 9.1 °C (48.4 °F) and a maximum of 23.2 °C (73.8 °F). On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 4.5 °C (40.5 °F). However, it dropped to 0 °C (32 °F) in April 1999.On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 32 °C (89.5 °F). However, it reached 37.2 °C (99 °F) in April 2009.Precipitation amounts to 25 mm (1 in), distributed over 5 days.
The day lasts on average 13 hours and 10 minutes.
The average humidity is 52%.
The average wind speed is 13 kph (8 mph).
May is generally a warm month. However, there are remarkable differences between night and day. The average temperature is of 19.9 °C (68 °F), with a minimum of 12.1 °C (53.7 °F) and a maximum of 27.8 °C (82 °F). On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 8 °C (46.5 °F). However, it dropped to 5.6 °C (42.1 °F) in May 2010.On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 36 °C (97 °F). However, it reached 42 °C (107.6 °F) in May 2009.Precipitation amounts to 15 mm (0.6 in), distributed over 3 days.
The day lasts on average 14 hours and 10 minutes. So the days are long.
The average humidity is 45%.
The average wind speed is 14 kph (9 mph).
June is generally a warm to hot month. However, there are remarkable differences between night and day. The average temperature is of 23.6 °C (74 °F), with a minimum of 15.1 °C (59.2 °F) and a maximum of 32.1 °C (89.7 °F). On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 11 °C (51.5 °F). However, it dropped to 7.8 °C (46 °F) in June 1991.On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 40 °C (104 °F). However, it reached 43.9 °C (111 °F) in June 2009.Precipitation amounts to only 5 mm (0.2 in), and all occurs in one day.
The day lasts on average 14 hours and 40 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 40%.
The average wind speed is 15 kph (9 mph).
July, the hottest month of the year, is generally a warm to hot month. However, there are remarkable differences between night and day. The average temperature is of 26.0 °C (79 °F), with a minimum of 17.1 °C (62.7 °F) and a maximum of 35 °C (95 °F). On the coldest nights of the month, the temperature usually drops to around 14 °C (57 °F). However, it dropped to 11.1 °C (52 °F) in July 1999.On the warmest days of the month, the temperature usually reaches around 41 °C (106 °F). However, it reached 45 °C (113 °F) in July 2006.Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 14 hours and 25 minutes. So the days are long.
The average humidity is 38%.
The average wind speed is 14 kph (8 mph).
August is generally a warm to hot month. However, there are remarkable differences between night and day. The average temperature is of 25.4 °C (78 °F), with a minimum of 16.7 °C (62 °F) and a maximum of 34.2 °C (93.5 °F). On the coldest nights of the month, the temperature usually drops to around 14 °C (57 °F). However, it dropped to 11.1 °C (52 °F) in August 2010.On the warmest days of the month, the temperature usually reaches around 40 °C (104.5 °F). However, it reached 43.9 °C (111 °F) in August 2020.Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 13 hours and 30 minutes.
The average humidity is 40%.
The average wind speed is 13 kph (8 mph).
September is generally a warm to hot month. However, there are remarkable differences between night and day. The average temperature is of 23.2 °C (74 °F), with a minimum of 14.8 °C (58.6 °F) and a maximum of 31.7 °C (89.1 °F). On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 10.5 °C (51 °F). However, it dropped to 7.2 °C (45 °F) in September 2007.On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 38 °C (100.5 °F). However, it reached 42.2 °C (108 °F) in September 2017.Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 12 hours and 25 minutes.
The average humidity is 43%.
The average wind speed is 11 kph (7 mph).
October is generally a warm month. However, there are remarkable differences between night and day. The average temperature is of 18.5 °C (65 °F), with a minimum of 10.8 °C (51.5 °F) and a maximum of 26.1 °C (79 °F). On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 5.5 °C (42 °F). However, it dropped to 2 °C (35.6 °F) in October 1996.On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 33 °C (91.5 °F). However, it reached 37.2 °C (99 °F) in October 2001.Precipitation amounts to 15 mm (0.6 in), distributed over 2 days.
The day lasts on average 11 hours and 10 minutes.
The average humidity is 52%.
The average wind speed is 9 kph (6 mph).
November is generally a mild month. The average temperature is of 12.5 °C (54 °F), with a minimum of 6.2 °C (43.2 °F) and a maximum of 18.7 °C (65.7 °F). On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 0.5 °C (33 °F). However, it dropped to -3 °C (26.6 °F) in November 2003.On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 25.5 °C (78 °F). However, it reached 29 °C (84.2 °F) in November 1997.Precipitation amounts to 25 mm (1 in), distributed over 6 days.
The day lasts on average 10 hours and 5 minutes.
The average humidity is 69%.
The average wind speed is 7 kph (5 mph).
December, the coldest month of the year, is generally a mild month. The average temperature is of 8.6 °C (47 °F), with a minimum of 3.7 °C (38.6 °F) and a maximum of 13.4 °C (56.2 °F). On the coldest nights of the month, the temperature usually drops to around -1.5 °C (29 °F). However, it dropped to -6.1 °C (21 °F) in December 1998.On the warmest days of the month, the temperature usually reaches around 18.5 °C (65.5 °F). However, it reached 21.7 °C (71.1 °F) in December 2014.Precipitation amounts to 55 mm (2.2 in), distributed over 9 days.
The day lasts on average 9 hours and 35 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 77%. Hence, the air is normally humid.
The average wind speed is 8 kph (5 mph).
