San Pasqual Battlefield State Historic Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the San Pasqual Battlefield State Historic Park clear sky chart from 2005-11-05 to 2017-09-15.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
76%
16230
33%
46955
29%
16188
78%
16188
47%
24787

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
69%
716
30%
2322
28%
716
74%
716
42%
1201
January16th to endNight
65%
768
35%
2304
31%
768
71%
768
38%
1280
February1st to 15thNight
69%
698
34%
2110
34%
698
74%
698
44%
1113
February16th to endNight
61%
632
28%
1895
32%
632
62%
632
31%
1145
March1st to 15thNight
69%
720
30%
2160
33%
720
72%
720
40%
1190
March16th to endNight
73%
768
28%
2037
25%
768
75%
768
43%
1175
April1st to 15thNight
66%
719
26%
1799
19%
719
67%
719
42%
1097
April16th to endNight
73%
720
30%
1800
19%
720
74%
720
48%
1048
May1st to 15thNight
72%
581
29%
1661
21%
581
73%
581
42%
949
May16th to endNight
69%
561
27%
1685
21%
561
70%
561
39%
967
June1st to 15thNight
79%
540
28%
1620
24%
540
79%
540
44%
887
June16th to endNight
93%
540
35%
1620
31%
540
93%
540
67%
696
July1st to 15thNight
90%
510
27%
1530
23%
510
90%
510
55%
744
July16th to endNight
89%
629
30%
1653
23%
591
88%
591
52%
854
August1st to 15thNight
89%
717
34%
1790
22%
713
90%
713
66%
894
August16th to endNight
93%
764
39%
1910
28%
764
93%
764
67%
960
September1st to 15thNight
89%
719
36%
1871
30%
719
89%
719
62%
938
September16th to endNight
88%
656
45%
1815
43%
656
89%
656
68%
810
October1st to 15thNight
79%
660
37%
1815
35%
660
81%
660
54%
938
October16th to endNight
76%
704
37%
2107
38%
704
78%
704
47%
1075
November1st to 15thNight
80%
700
35%
2275
39%
700
82%
700
51%
1052
November16th to endNight
77%
720
35%
2340
37%
720
80%
720
44%
1171
December1st to 15thNight
68%
720
33%
2340
35%
720
71%
720
39%
1241
December16th to endNight
62%
768
32%
2496
31%
768
68%
768
37%
1362

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
5%312213346%65%
47763
Night
6%413213346%61%
47158
TransparencyDay
21%2416%26%28%
47464
Night
24%2415%23%28%
46958
SeeingDay
7%6%26%39%15%4
5911
Night
7%25%31%39%12%
16243

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
10%323322245%59%
1614
16th to endDay
10%413323445%56%
1920
February1st to 15thDay
8%413324435%58%
1751
16th to endDay
14%6%2442345%6%46%
1579
March1st to 15thDay
6%42331345%8%56%
1800
16th to endDay
6%223423248%59%
2183
April1st to 15thDay
8%423324346%56%
2149
16th to endDay
6%312212246%66%
2160
May1st to 15thDay
7%413213345%62%
2286
16th to endDay
5%422212246%65%
2429
June1st to 15thDay
5%313212235%68%
2340
16th to endDay
1111222383%
2340
July1st to 15thDay
121232335%6%68%
2340
16th to endDay
22121336%8%66%
2398
August1st to 15thDay
12211223477%
2160
16th to endDay
11212335%76%
2292
September1st to 15thDay
111212235%76%
2077
16th to endDay
11211222478%
1815
October1st to 15thDay
6%313313345%64%
1815
16th to endDay
6%31221132470%
1763
November1st to 15thDay
5%212223345%65%
1584
16th to endDay
8%213213346%62%
1620
December1st to 15thDay
9%413424349%53%
1620
16th to endDay
14%422323335%54%
1728
January1st to 15thNight
7%313334346%59%
2322
16th to endNight
11%423323235%57%
2304
February1st to 15thNight
8%323313345%60%
2101
16th to endNight
14%5%2432334448%
1895
March1st to 15thNight
9%5%2322335%7%55%
2160
16th to endNight
7%423324448%53%
2037
April1st to 15thNight
10%6%23312447%52%
1799
16th to endNight
8%5%13223336%60%
1800
May1st to 15thNight
7%7%2222335%8%54%
1661
16th to endNight
7%8%24313246%54%
1684
June1st to 15thNight
35%2232435%7%59%
1620
16th to endNight
114345%76%
1620
July1st to 15thNight
14221445%5%66%
1620
16th to endNight
2112225%5%6%8%61%
1766
August1st to 15thNight
22121325%8%69%
1800
16th to endNight
21213445%73%
1910
September1st to 15thNight
132212346%71%
1871
16th to endNight
21111113379%
1815
October1st to 15thNight
5%212212346%65%
1815
16th to endNight
6%413312335%63%
2107
November1st to 15thNight
4312213335%67%
2275
16th to endNight
5%313323336%61%
2340
December1st to 15thNight
9%42422235%7%55%
2340
16th to endNight
12%5%23312245%56%
2496

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
28%2313%25%27%
1615
16th to endDay
29%36%14%16%29%
1920
February1st to 15thDay
29%2313%23%27%
1751
16th to endDay
38%25%16%23%13%
1579
March1st to 15thDay
26%25%20%22%23%
1800
16th to endDay
25%28%25%21%16%
2183
April1st to 15thDay
30%25%24%26%11%
2149
16th to endDay
20%16%24%27%19%
2160
May1st to 15thDay
24%2421%27%19%
2286
16th to endDay
22%1424%34%12%
2432
June1st to 15thDay
20%2216%31%26%
2340
16th to endDay
8%116%22%58%
2340
July1st to 15thDay
15%3212%25%39%
2201
16th to endDay
16%39%22%29%18%
2248
August1st to 15thDay
11%2115%34%34%
2146
16th to endDay
11%2211%35%35%
2292
September1st to 15thDay
12%2210%35%37%
2077
16th to endDay
11%110%34%40%
1815
October1st to 15thDay
23%2216%27%26%
1815
16th to endDay
20%1312%20%41%
1763
November1st to 15thDay
20%16%14%20%36%
1584
16th to endDay
22%2414%20%35%
1620
December1st to 15thDay
29%18%15%17%26%
1620
16th to endDay
33%16%15%23%18%
1728
January1st to 15thNight
26%2413%21%30%
2322
16th to endNight
31%26%12%16%31%
2304
February1st to 15thNight
26%16%14%20%29%
2112
16th to endNight
38%2315%23%16%
1895
March1st to 15thNight
29%2419%19%23%
2160
16th to endNight
28%38%19%22%17%
2037
April1st to 15thNight
32%26%23%22%12%
1799
16th to endNight
27%26%21%21%21%
1800
May1st to 15thNight
29%36%18%22%19%
1662
16th to endNight
31%35%21%24%14%
1685
June1st to 15thNight
25%4312%32%21%
1620
16th to endNight
9%416%22%55%
1620
July1st to 15thNight
17%4310%25%39%
1530
16th to endNight
18%5%8%20%30%16%
1653
August1st to 15thNight
13%3216%35%29%
1790
16th to endNight
12%4310%32%37%
1910
September1st to 15thNight
15%3210%31%36%
1871
16th to endNight
12%111%34%40%
1815
October1st to 15thNight
21%2418%28%25%
1815
16th to endNight
24%2110%20%39%
2107
November1st to 15thNight
20%1416%17%39%
2275
16th to endNight
25%2315%18%34%
2340
December1st to 15thNight
29%26%15%19%26%
2340
16th to endNight
31%28%14%20%22%
2496

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
27%312%44%11%
93
16th to endDay
16%9%33%33%5%2
288
February1st to 15thDay
9%9%34%32%12%1
266
16th to endDay
18%12%31%28%7%
238
March1st to 15thDay
9%12%27%30%14%4
270
16th to endDay
6%12%34%30%12%4
288
April1st to 15thDay
10%15%33%27%9%3
269
16th to endDay
6%14%40%26%8%3
270
May1st to 15thDay
14%9%31%33%7%2
288
16th to endDay
10%9%32%32%13%1
330
June1st to 15thDay
5%329%37%20%3
315
16th to endDay
120%47%21%8%
315
July1st to 15thDay
2113%48%26%7%
305
16th to endDay
47%54%22%10%
327
August1st to 15thDay
1114%53%20%7%
315
16th to endDay
1110%55%21%8%
332
September1st to 15thDay
3125%51%12%5%
312
16th to endDay
35%30%43%11%4
255
October1st to 15thDay
410%40%32%10%1
255
16th to endDay
11%5%28%34%16%3
214
November1st to 15thDay
5%420%30%34%5%
90
16th to endDay
10%5%24%46%12%1
90
December1st to 15thDay
4318%40%28%4
90
16th to endDay
21%5%18%38%14%1
96
January1st to 15thNight
8%212%37%27%11%
720
16th to endNight
13%29%39%27%7%
768
February1st to 15thNight
10%36%39%29%10%
704
16th to endNight
16%29%39%25%6%
632
March1st to 15thNight
10%39%38%30%6%
720
16th to endNight
8%35%38%35%8%
768
April1st to 15thNight
11%48%41%28%6%
719
16th to endNight
9%47%36%32%10%
720
May1st to 15thNight
9%36%35%36%8%
582
16th to endNight
9%5%7%30%41%6%
563
June1st to 15thNight
5%26%37%41%6%
540
16th to endNight
2132%55%7%
540
July1st to 15thNight
1116%66%13%
510
16th to endNight
2110%63%21%
629
August1st to 15thNight
1316%57%21%
717
16th to endNight
1110%57%29%
764
September1st to 15thNight
3117%58%18%
719
16th to endNight
31228%47%16%
656
October1st to 15thNight
6%25%38%37%10%
660
16th to endNight
8%2428%37%18%
704
November1st to 15thNight
6%15%37%35%14%
700
16th to endNight
7%16%36%31%16%
720
December1st to 15thNight
11%29%39%25%11%
720
16th to endNight
16%210%36%24%8%
768
Page generated at 2017-09-15 21:58:33. Version ac04

Copyright 2017 A. Danko


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