Oak Glen Preserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oak Glen Preserve clear sky chart from 2005-11-05 to 2017-09-22.

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
62%
16202
33%
47026
25%
16163
69%
16163
50%
23760

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
50%
716
29%
2327
22%
716
61%
716
40%
1192
January16th to endNight
48%
768
31%
2328
22%
768
59%
768
36%
1328
February1st to 15thNight
52%
698
31%
2108
27%
698
61%
698
40%
1149
February16th to endNight
43%
632
28%
1895
24%
632
52%
632
30%
1156
March1st to 15thNight
49%
720
28%
2160
22%
720
60%
720
38%
1179
March16th to endNight
52%
768
29%
2037
20%
768
59%
768
44%
1168
April1st to 15thNight
43%
719
28%
1799
13%
719
50%
719
41%
1068
April16th to endNight
49%
720
32%
1800
14%
720
57%
720
49%
1005
May1st to 15thNight
58%
560
33%
1640
20%
560
64%
560
54%
775
May16th to endNight
55%
561
32%
1685
20%
561
62%
561
53%
794
June1st to 15thNight
67%
540
32%
1620
24%
540
72%
540
66%
691
June16th to endNight
77%
540
37%
1620
30%
540
81%
540
81%
617
July1st to 15thNight
86%
510
30%
1530
26%
510
87%
510
67%
650
July16th to endNight
84%
594
31%
1621
25%
559
84%
559
56%
787
August1st to 15thNight
89%
717
37%
1790
24%
713
90%
713
75%
835
August16th to endNight
90%
764
43%
1910
29%
764
90%
764
76%
890
September1st to 15thNight
86%
720
39%
1869
30%
720
89%
720
72%
863
September16th to endNight
80%
683
47%
1890
38%
683
87%
683
76%
795
October1st to 15thNight
64%
660
37%
1815
30%
660
72%
660
55%
919
October16th to endNight
69%
704
38%
2131
35%
704
76%
704
54%
1001
November1st to 15thNight
66%
700
34%
2275
31%
700
75%
700
54%
1022
November16th to endNight
61%
720
34%
2340
34%
720
69%
720
43%
1176
December1st to 15thNight
50%
720
31%
2340
25%
720
61%
720
34%
1295
December16th to endNight
43%
768
31%
2496
25%
768
54%
768
32%
1405

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%412213335%65%
47848
Night
4412212335%66%
47228
TransparencyDay
19%36%15%26%28%
47546
Night
20%36%14%26%28%
47031
SeeingDay
6%12%35%33%8%2
5896
Night
5%5%21%34%26%6%
16215

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
8%5%1322335%6%58%
1611
16th to endDay
10%7%23223446%52%
1893
February1st to 15thDay
7%6%23323346%56%
1751
16th to endDay
11%11%34322235%48%
1579
March1st to 15thDay
7%7%12223447%56%
1800
16th to endDay
5%6%2332335%7%54%
2183
April1st to 15thDay
8%6%23222435%57%
2149
16th to endDay
4312212347%65%
2160
May1st to 15thDay
3313313346%65%
2310
16th to endDay
321213347%68%
2429
June1st to 15thDay
12111333474%
2340
16th to endDay
1111111285%
2340
July1st to 15thDay
2112213336%70%
2340
16th to endDay
333323447%63%
2434
August1st to 15thDay
11121223476%
2160
16th to endDay
11221333375%
2292
September1st to 15thDay
2112212335%73%
2089
16th to endDay
1112222281%
1882
October1st to 15thDay
5%31211324467%
1815
16th to endDay
32221243471%
1739
November1st to 15thDay
441321232467%
1584
16th to endDay
7%413323336%60%
1620
December1st to 15thDay
7%7%2433437%7%48%
1620
16th to endDay
12%6%3432433453%
1728
January1st to 15thNight
7%5%14313347%57%
2327
16th to endNight
9%6%24313345%54%
2328
February1st to 15thNight
8%8%23212335%58%
2101
16th to endNight
10%11%33323445%48%
1895
March1st to 15thNight
5%8%22323437%55%
2160
16th to endNight
47%23213348%57%
2037
April1st to 15thNight
5%8%12213436%60%
1799
16th to endNight
333223325%68%
1800
May1st to 15thNight
131213346%71%
1640
16th to endNight
132212336%72%
1684
June1st to 15thNight
12111235%78%
1620
16th to endNight
111288%
1620
July1st to 15thNight
21121223377%
1620
16th to endNight
2212213346%68%
1731
August1st to 15thNight
112222480%
1800
16th to endNight
1111121283%
1910
September1st to 15thNight
111111222479%
1869
16th to endNight
111111386%
1890
October1st to 15thNight
4212212325%69%
1815
16th to endNight
111231333372%
2131
November1st to 15thNight
241221313469%
2275
16th to endNight
45%23313335%61%
2340
December1st to 15thNight
8%7%24323347%51%
2340
16th to endNight
10%7%24213335%53%
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
25%37%14%26%22%
1612
16th to endDay
30%46%14%21%22%
1893
February1st to 15thDay
26%45%15%24%22%
1751
16th to endDay
36%36%15%25%13%
1579
March1st to 15thDay
22%47%20%24%20%
1800
16th to endDay
26%5%9%20%24%13%
2183
April1st to 15thDay
28%37%20%29%11%
2149
16th to endDay
19%29%19%31%17%
2160
May1st to 15thDay
19%36%19%28%22%
2310
16th to endDay
17%38%22%33%15%
2432
June1st to 15thDay
12%16%15%31%32%
2340
16th to endDay
7%13419%61%
2340
July1st to 15thDay
13%36%10%21%43%
2201
16th to endDay
19%5%8%17%23%26%
2281
August1st to 15thDay
10%3412%25%42%
2146
16th to endDay
11%4410%33%35%
2292
September1st to 15thDay
11%47%9%30%37%
2089
16th to endDay
10%1211%30%43%
1882
October1st to 15thDay
18%3414%28%30%
1815
16th to endDay
16%35%10%25%38%
1739
November1st to 15thDay
19%26%13%30%26%
1584
16th to endDay
24%35%12%25%28%
1620
December1st to 15thDay
28%5%8%17%19%20%
1620
16th to endDay
32%37%16%22%16%
1728
January1st to 15thNight
25%46%15%22%26%
2327
16th to endNight
31%47%12%18%24%
2328
February1st to 15thNight
28%35%14%23%25%
2112
16th to endNight
36%4414%22%15%
1895
March1st to 15thNight
27%47%17%22%21%
2160
16th to endNight
25%5%8%20%24%14%
2037
April1st to 15thNight
29%38%21%23%14%
1799
16th to endNight
23%35%18%32%17%
1800
May1st to 15thNight
15%39%19%32%18%
1641
16th to endNight
17%39%22%32%15%
1685
June1st to 15thNight
11%15%14%30%36%
1620
16th to endNight
5%137%23%58%
1620
July1st to 15thNight
9%45%10%22%47%
1530
16th to endNight
16%48%19%24%25%
1621
August1st to 15thNight
8%2414%29%40%
1790
16th to endNight
8%2310%36%38%
1910
September1st to 15thNight
9%35%11%31%39%
1869
16th to endNight
8%211%32%44%
1890
October1st to 15thNight
19%2414%31%27%
1815
16th to endNight
17%248%26%39%
2131
November1st to 15thNight
17%26%13%30%30%
2275
16th to endNight
24%35%13%22%31%
2340
December1st to 15thNight
30%45%14%20%22%
2340
16th to endNight
31%48%14%23%18%
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
30%10%33%24%11
90
16th to endDay
16%17%31%29%31
261
February1st to 15thDay
9%20%31%28%9%
266
16th to endDay
19%25%31%20%3
238
March1st to 15thDay
10%19%37%22%7%2
270
16th to endDay
9%22%38%21%8%
288
April1st to 15thDay
12%25%38%15%5%1
269
16th to endDay
6%30%40%18%4
270
May1st to 15thDay
9%19%37%27%42
288
16th to endDay
417%44%26%5%1
330
June1st to 15thDay
211%44%32%6%2
315
16th to endDay
3336%39%13%3
315
July1st to 15thDay
1129%48%14%3
305
16th to endDay
3121%55%13%6%
327
August1st to 15thDay
1336%44%8%5%
315
16th to endDay
2128%50%12%5%
332
September1st to 15thDay
4443%37%9%
315
16th to endDay
28%39%38%8%2
280
October1st to 15thDay
6%14%44%28%6%
255
16th to endDay
5%8%35%33%15%
201
November1st to 15thDay
311%22%31%30%2
90
16th to endDay
8%15%33%31%11%
90
December1st to 15thDay
314%32%37%11%1
90
16th to endDay
14%15%35%22%11%
96
January1st to 15thNight
8%5%28%32%18%6%
720
16th to endNight
12%5%28%30%20%3
768
February1st to 15thNight
9%5%26%33%20%3
704
16th to endNight
14%8%29%29%14%4
632
March1st to 15thNight
7%8%28%33%17%4
720
16th to endNight
5%8%29%32%19%4
768
April1st to 15thNight
6%13%32%28%14%3
719
16th to endNight
5%10%32%27%19%5%
720
May1st to 15thNight
37%27%41%17%2
561
16th to endNight
28%30%34%21%2
563
June1st to 15thNight
1425%46%20%2
540
16th to endNight
19%56%22%1
540
July1st to 15thNight
16%45%41%3
510
16th to endNight
16%41%44%4
594
August1st to 15thNight
1439%46%8%
717
16th to endNight
2429%50%12%
764
September1st to 15thNight
17%34%44%11%
720
16th to endNight
1114%32%39%10%
683
October1st to 15thNight
45%21%35%27%6%
660
16th to endNight
25%18%32%28%13%
704
November1st to 15thNight
4220%36%27%7%
700
16th to endNight
6%5%21%34%22%9%
720
December1st to 15thNight
10%5%27%30%21%4
720
16th to endNight
12%9%29%26%17%4
768
Page generated at 2017-09-23 03:43:39. Version ac04

Copyright 2017 A. Danko


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