Climate
 The climate along
and near the C. Hart Merriam elevation
gradient is variable, both by season
and from one year to the next. Generally,
it is considered semi-arid. Nevertheless,
the wide range in elevation results in
local climates that vary from tundra
to semi-desert. Even within these local
climates, many climatologists agree that
several "microclimates" (really
more a weather phenomena than a climatic
one) occur over very short distances
due to the presence of local topographic
features. For example, snow in Hart Prairie,
on the west side of San Francisco Mountain,
can be contrasted by sunshine and clear
skies just 10 linear miles away on the
east side near Mt. Elden.
Generally though, summer weather is defined
by monsoon storms during the months of
July through September. This usually follows
a dry, hot month of June. Spring is usually
mild, with sporadic rain showers through
April and May, and occasionally snow. Winter
snow levels range from several inches to
several feet, with temperatures ranging
from -15°F to 30°F during the coldest
months (generally November through January).
Relative humidity can be as low as 6% during
the driest months of May and June, resulting
in extremely dry conditions.
Climate and
C. Hart Merriam's Life Zones
Climate in the vicinity of
San Francisco Mountain can be delineated
into zones that correspond to Merriam's
life zones:
Alpine-tundra life zone: At
elevations above 3,000m, the average annual
minimum temperature is usually at or below
freezing. Average annual precipitation
levels are high, upwards of 25 inches,
most of it in the form of snowfall. Winds
are extreme above 3,500m, above the tree
line.
Mixed Conifer life zone: At
elevations ranging from 2,500m - 3,000m,
the average annual maximum temperature
is about 56°F, while the average annual
minimum temperature is about 32°F.
Average annual precipitation is about 20
inches, occurring mostly during winter
storms and summer monsoons.
Ponderosa Pine life zone: At
elevations ranging from 2,000m - 2,500m,
average annual maximum temperature is about
66°F and average annual minimum temperature
is about 37°F. Average annual precipitation
is about 14 inches, with the majority of
surface runoff in these areas coming from
winter precipitation, while only a small
amount of summer precipitation contributes
to streamflow. Transpiration rates are
high (about 20 inches per year) in the
pine types and low soil moisture content
is common.
Pinyon-Juniper life zone: At
elevations ranging from 1,500m - 2,000m,
average annual maximum temperature is about
66°F and average annual minimum temperature
is about 39°F. Average annual precipitation
is about 10 inches, though annual precipitation
levels range from 12 to 24 inches in a
normal year. Evapotranspiration rates are
high, at about 16 inches per year, and
the months of December through February
being the only months when precipitation
is greater than evapotranspiration. ]
Grassland life zone: At elevations
ranging from 1,000m - 1,500m, average annual
maximum temperature is about 69°F and
average annual minimum temperature is about
44°F. Average annual precipitation
is about 7 inches.
Great Basin Desert life zone:
At elevations below 1,500m, average annual
maximum temperature is about 65°F and
average annual minimum temperature is about
39°F. Average annual precipitation
is about 5 inches.
Elevational Gradient Summary Weather Data
|
Jan |
Feb |
Mar |
Apr |
May |
Jun |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
| Great
Basin |
|
|
|
|
|
|
|
|
|
|
|
|
| precip |
0.2 |
0.87 |
0 |
0.58 |
0 |
0.04 |
0.365 |
0.158 |
0.565 |
0.44 |
1.04 |
0.2 |
| tmax avg |
49 |
50.8 |
66.1 |
67.6 |
83 |
90.4 |
102 |
88 |
84.8 |
75.9 |
53.2 |
46.2 |
| tmin avg |
25.1 |
31.6 |
33.7 |
38.7 |
55 |
58.1 |
75 |
69 |
55.3 |
46.2 |
30.1 |
22.6 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| Grassland |
|
|
|
|
|
|
|
|
|
|
|
|
| precip |
0.52 |
0.33 |
0.2 |
0.297 |
0.12 |
0.297 |
0.683 |
1.64 |
0.46 |
0.27 |
1.05 |
0.236 |
| tmax avg |
47.5 |
48.2 |
60 |
64.9 |
79 |
86.4 |
92.7 |
84.3 |
82.5 |
74.4 |
51.6 |
43.8 |
| tmin avg |
26.1 |
25.3 |
35.4 |
37.7 |
51.3 |
59.8 |
65.6 |
62.3 |
56.1 |
46.7 |
30.8 |
23.5 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| Pinyon-Juniper |
|
|
|
|
|
|
|
|
|
|
|
|
| precip |
1.62 |
0.27 |
ND |
0.795 |
0.335 |
0.045 |
0.593 |
2.25 |
0.77 |
0.52 |
0.835 |
0.775 |
| tmax avg |
45 |
47.8 |
58 |
61.2 |
75.5 |
84.4 |
82.6 |
80.4 |
78.3 |
71.8 |
50.7 |
40 |
| tmin avg |
25.9 |
22 |
28 |
32.9 |
45.7 |
54.4 |
54.6 |
55.3 |
51.4 |
42.8 |
26.2 |
20.6 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| Ponderosa |
|
|
|
|
|
|
|
|
|
|
|
|
| precip |
ND |
0.01 |
0.43 |
0.833 |
1.6 |
0.297 |
1.91 |
2.74 |
0.45 |
0.45 |
1.8 |
0.485 |
| tmax avg |
38 |
37.8 |
52.7 |
55.4 |
66.1 |
79.7 |
83.7 |
74.7 |
76.1 |
69 |
50.9 |
40 |
| tmin avg |
24 |
13.5 |
26.3 |
31.8 |
40.5 |
49.9 |
57.5 |
52.2 |
51.2 |
28.8 |
21.1 |
17.6 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| Mixed
Conifer |
|
|
|
|
|
|
|
|
|
|
|
|
| precip |
1.72 |
4.67 |
2.29 |
1.19 |
0.0433 |
0.0267 |
2.08 |
1.44 |
1.03 |
2.53 |
1.2 |
1.54 |
| tmax avg |
36 |
37.7 |
43.2 |
49.6 |
62.9 |
70.3 |
77.1 |
69.2 |
68.4 |
63.5 |
44.2 |
41.1 |
| tmin avg |
23.9 |
19.9 |
21.6 |
27.9 |
36.1 |
41.6 |
48.1 |
46.3 |
40.9 |
36.1 |
24.8 |
19.5 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| ND
= No Data |
|
Interpolated
Data |
|
|
|
|
|
|
|
|
WARNING: This
spreadsheet summarizes data collected from 2001
until 2005, because this coincides with a period
of intense drought precipitation averages are unlikely
to reflect long term averages.
Monthly average
precipitation is likely highly skewed from long
term averages since most precipitation fell in
rare and localized events.
Due to technical difficulties precipitation
due to snow fall may be under measured.
This data is provided "as is" and
no warrantee as to accuracy is expressed or implied.
|
