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 2018-04-23.

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%
17103
33%
49552
30%
17061
78%
17061
47%
26177

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
68%
776
29%
2516
28%
776
73%
776
40%
1326
January16th to endNight
67%
832
35%
2496
32%
832
72%
832
40%
1365
February1st to 15thNight
71%
758
34%
2290
34%
758
75%
758
44%
1203
February16th to endNight
62%
684
30%
2051
33%
684
64%
684
33%
1219
March1st to 15thNight
68%
780
28%
2340
31%
780
70%
780
38%
1315
March16th to endNight
74%
832
27%
2207
25%
832
75%
832
43%
1282
April1st to 15thNight
66%
779
27%
1949
20%
779
67%
779
41%
1200
April16th to endNight
73%
744
31%
1860
19%
744
74%
744
48%
1081
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%
720
36%
1872
30%
720
89%
720
61%
939
September16th to endNight
87%
716
46%
1980
44%
716
88%
716
67%
898
October1st to 15thNight
80%
720
36%
1980
34%
720
82%
720
54%
1017
October16th to endNight
76%
768
39%
2298
40%
768
78%
768
47%
1166
November1st to 15thNight
79%
760
33%
2470
37%
760
81%
760
49%
1175
November16th to endNight
78%
780
36%
2535
39%
780
80%
780
44%
1271
December1st to 15thNight
69%
780
33%
2535
35%
780
72%
780
40%
1316
December16th to endNight
64%
832
34%
2704
33%
832
69%
832
38%
1453

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%
49952
Night
6%413213346%61%
49755
TransparencyDay
21%2416%26%28%
49653
Night
24%3415%23%28%
49555
SeeingDay
7%6%25%38%16%4
6698
Night
7%25%32%38%12%
17116

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%323322345%58%
1749
16th to endDay
10%413323345%57%
2080
February1st to 15thDay
8%31332443459%
1901
16th to endDay
13%5%24423446%46%
1709
March1st to 15thDay
7%42332345%8%55%
1950
16th to endDay
6%223423348%58%
2365
April1st to 15thDay
7%41332435%6%56%
2329
16th to endDay
6%312212247%66%
2214
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%
2087
16th to endDay
21111222478%
1980
October1st to 15thDay
5%313312345%65%
1980
16th to endDay
6%31221133370%
1922
November1st to 15thDay
5%31232335%5%62%
1719
16th to endDay
8%313213346%62%
1755
December1st to 15thDay
8%412314349%55%
1755
16th to endDay
13%412323335%55%
1872
January1st to 15thNight
7%413333347%56%
2516
16th to endNight
10%423322235%58%
2496
February1st to 15thNight
8%323313345%60%
2281
16th to endNight
14%5%24323345%50%
2051
March1st to 15thNight
10%42322335%7%53%
2340
16th to endNight
7%413324449%52%
2207
April1st to 15thNight
9%6%23323447%51%
1949
16th to endNight
8%5%13223336%60%
1860
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%
1872
16th to endNight
221111123378%
1980
October1st to 15thNight
5%212212346%66%
1980
16th to endNight
6%413312335%64%
2298
November1st to 15thNight
4313223346%64%
2470
16th to endNight
5%313324336%60%
2535
December1st to 15thNight
9%32422235%7%56%
2535
16th to endNight
11%423312245%57%
2704

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%2314%24%25%
1750
16th to endDay
28%36%15%16%29%
2080
February1st to 15thDay
28%2313%23%28%
1901
16th to endDay
38%2416%23%14%
1709
March1st to 15thDay
27%25%21%20%22%
1950
16th to endDay
26%28%24%22%15%
2365
April1st to 15thDay
29%26%23%25%12%
2329
16th to endDay
19%16%23%27%19%
2214
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%
2087
16th to endDay
11%110%35%40%
1980
October1st to 15thDay
22%3215%28%28%
1980
16th to endDay
20%1311%19%42%
1922
November1st to 15thDay
22%26%15%19%33%
1719
16th to endDay
23%2313%21%35%
1755
December1st to 15thDay
28%17%14%17%29%
1755
16th to endDay
33%16%15%23%20%
1872
January1st to 15thNight
27%3413%21%28%
2516
16th to endNight
30%25%12%16%32%
2496
February1st to 15thNight
26%16%13%21%30%
2292
16th to endNight
36%2314%25%16%
2051
March1st to 15thNight
31%25%19%18%22%
2340
16th to endNight
29%38%19%22%17%
2207
April1st to 15thNight
32%36%23%21%13%
1949
16th to endNight
26%26%20%22%21%
1860
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%
1872
16th to endNight
13%110%34%39%
1980
October1st to 15thNight
20%3317%28%26%
1980
16th to endNight
24%2110%19%41%
2298
November1st to 15thNight
22%2417%16%36%
2470
16th to endNight
25%2315%19%34%
2535
December1st to 15thNight
28%26%14%18%29%
2535
16th to endNight
30%27%13%22%23%
2704

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
24%210%42%18%2
138
16th to endDay
13%8%30%31%11%4
352
February1st to 15thDay
7%9%30%32%15%3
326
16th to endDay
18%12%29%29%9%1
290
March1st to 15thDay
10%11%29%31%12%3
330
16th to endDay
6%11%33%31%12%3
352
April1st to 15thDay
10%13%31%29%11%3
329
16th to endDay
6%14%40%25%8%3
288
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%
315
16th to endDay
46%30%41%13%4
315
October1st to 15thDay
49%36%34%14%
315
16th to endDay
10%426%33%20%4
272
November1st to 15thDay
8%419%36%28%3
135
16th to endDay
13%418%40%17%5%
135
December1st to 15thDay
3419%37%29%5%
135
16th to endDay
15%415%34%22%7%
144
January1st to 15thNight
9%212%37%27%11%
780
16th to endNight
12%28%39%28%7%
832
February1st to 15thNight
10%36%38%29%11%
764
16th to endNight
15%29%39%25%6%
684
March1st to 15thNight
11%38%39%30%6%
780
16th to endNight
8%35%39%34%8%
832
April1st to 15thNight
11%48%41%28%6%
779
16th to endNight
9%47%36%32%9%
744
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%
720
16th to endNight
3229%46%16%
716
October1st to 15thNight
5%2437%39%10%
720
16th to endNight
9%2428%37%18%
768
November1st to 15thNight
6%15%40%33%13%
760
16th to endNight
7%16%36%32%16%
780
December1st to 15thNight
10%210%40%26%10%
780
16th to endNight
14%29%36%26%9%
832
Page generated at 2018-04-24 07:03:03. Version ac04

Copyright 2018 A. Danko


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