Banning
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Banning clear sky chart from 2005-11-05 to 2017-04-07.

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
61%
15625
33%
45438
25%
15585
68%
15585
48%
23376

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
52%
716
29%
2327
23%
716
63%
716
39%
1203
January16th to endNight
50%
768
31%
2328
23%
768
61%
768
35%
1338
February1st to 15thNight
53%
698
32%
2108
26%
698
63%
698
40%
1146
February16th to endNight
43%
632
28%
1895
24%
632
52%
632
30%
1154
March1st to 15thNight
49%
720
29%
2157
23%
720
60%
720
37%
1196
March16th to endNight
52%
768
29%
2040
20%
768
60%
768
44%
1160
April1st to 15thNight
41%
687
27%
1719
12%
687
49%
687
38%
1060
April16th to endNight
46%
660
28%
1650
12%
660
53%
660
46%
947
May1st to 15thNight
53%
513
33%
1503
21%
513
59%
513
48%
759
May16th to endNight
51%
514
27%
1541
17%
513
58%
513
45%
797
June1st to 15thNight
61%
495
33%
1485
24%
495
67%
495
58%
677
June16th to endNight
75%
495
35%
1485
28%
495
79%
495
80%
571
July1st to 15thNight
85%
465
31%
1395
27%
465
86%
465
63%
612
July16th to endNight
82%
549
30%
1492
23%
514
84%
514
54%
731
August1st to 15thNight
87%
657
39%
1640
25%
653
88%
653
76%
760
August16th to endNight
89%
700
41%
1750
28%
700
90%
700
74%
827
September1st to 15thNight
85%
660
40%
1716
31%
660
88%
660
70%
805
September16th to endNight
80%
656
45%
1815
38%
656
86%
656
73%
781
October1st to 15thNight
63%
660
38%
1815
28%
660
73%
660
53%
920
October16th to endNight
70%
704
38%
2126
35%
704
76%
704
52%
1020
November1st to 15thNight
67%
700
35%
2275
32%
700
75%
700
53%
1036
November16th to endNight
60%
720
35%
2340
34%
720
68%
720
42%
1175
December1st to 15thNight
51%
720
31%
2340
25%
720
61%
720
35%
1289
December16th to endNight
44%
768
32%
2496
26%
768
55%
768
33%
1412

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
4312212335%66%
45784
Night
4423312335%65%
45640
TransparencyDay
20%35%14%26%28%
45482
Night
22%35%14%25%28%
45443
SeeingDay
8%13%35%33%8%1
5229
Night
7%422%36%23%4
15637

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
6%5%1332235%5%59%
1611
16th to endDay
9%6%12323346%56%
1893
February1st to 15thDay
6%5%23322346%59%
1751
16th to endDay
10%8%36%322336%49%
1579
March1st to 15thDay
5%31231345%8%60%
1801
16th to endDay
5%5%2232345%7%57%
2181
April1st to 15thDay
6%7%23423245%56%
2044
16th to endDay
5%412312236%65%
1980
May1st to 15thDay
4313312235%67%
2117
16th to endDay
3312212337%67%
2221
June1st to 15thDay
1312111236%73%
2145
16th to endDay
111122185%
2145
July1st to 15thDay
2211213236%72%
2145
16th to endDay
2212223346%65%
2255
August1st to 15thDay
1121223479%
1980
16th to endDay
11121223477%
2100
September1st to 15thDay
1221222478%
1913
16th to endDay
11211112382%
1815
October1st to 15thDay
4313212235%68%
1815
16th to endDay
2412212235%70%
1741
November1st to 15thDay
331231224469%
1584
16th to endDay
6%412223336%61%
1620
December1st to 15thDay
7%5%1232445%7%54%
1620
16th to endDay
10%5%25%312345%56%
1728
January1st to 15thNight
6%314322336%60%
2327
16th to endNight
8%6%24422435%55%
2328
February1st to 15thNight
6%7%1431323461%
2101
16th to endNight
9%9%2442344449%
1895
March1st to 15thNight
5%6%3331335%6%56%
2157
16th to endNight
35%3441245%8%57%
2040
April1st to 15thNight
49%34424346%52%
1719
16th to endNight
5%5%33312225%62%
1650
May1st to 15thNight
3413313447%63%
1503
16th to endNight
26%34312235%63%
1540
June1st to 15thNight
313212126%73%
1485
16th to endNight
1111287%
1485
July1st to 15thNight
111213245%74%
1485
16th to endNight
2212323246%68%
1602
August1st to 15thNight
1111122480%
1650
16th to endNight
1112112382%
1750
September1st to 15thNight
11112123379%
1716
16th to endNight
22121383%
1815
October1st to 15thNight
241321232470%
1815
16th to endNight
24322233469%
2126
November1st to 15thNight
2322212235%69%
2275
16th to endNight
46%23312246%62%
2340
December1st to 15thNight
7%5%245%23347%53%
2340
16th to endNight
9%6%25%323225%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
26%46%12%28%23%
1612
16th to endDay
30%46%13%21%24%
1893
February1st to 15thDay
27%4414%25%23%
1751
16th to endDay
37%3414%25%13%
1579
March1st to 15thDay
22%47%20%25%20%
1801
16th to endDay
26%5%7%21%24%14%
2181
April1st to 15thDay
29%45%20%28%11%
2044
16th to endDay
21%26%19%30%19%
1980
May1st to 15thDay
20%27%18%27%24%
2117
16th to endDay
18%38%21%33%14%
2224
June1st to 15thDay
14%1416%28%33%
2145
16th to endDay
7%235%21%58%
2145
July1st to 15thDay
13%4411%21%44%
2006
16th to endDay
18%6%6%18%23%27%
2102
August1st to 15thDay
9%4313%27%42%
1966
16th to endDay
11%4410%34%35%
2100
September1st to 15thDay
11%348%29%41%
1913
16th to endDay
10%229%30%45%
1815
October1st to 15thDay
18%25%13%29%30%
1815
16th to endDay
17%349%24%40%
1741
November1st to 15thDay
18%26%14%29%28%
1584
16th to endDay
24%3411%25%30%
1620
December1st to 15thDay
28%5%7%17%20%21%
1620
16th to endDay
32%37%16%24%16%
1728
January1st to 15thNight
26%35%14%22%28%
2327
16th to endNight
32%46%11%18%26%
2328
February1st to 15thNight
28%3414%22%26%
2112
16th to endNight
37%4415%23%15%
1895
March1st to 15thNight
28%45%17%22%20%
2157
16th to endNight
26%48%21%23%15%
2040
April1st to 15thNight
32%38%20%21%13%
1719
16th to endNight
25%35%17%29%17%
1650
May1st to 15thNight
20%38%19%27%21%
1504
16th to endNight
24%28%21%29%12%
1541
June1st to 15thNight
15%25%13%28%34%
1485
16th to endNight
6%36%28%54%
1485
July1st to 15thNight
11%4410%22%46%
1395
16th to endNight
17%47%19%25%25%
1492
August1st to 15thNight
8%2316%29%40%
1640
16th to endNight
9%2211%35%37%
1750
September1st to 15thNight
10%249%30%41%
1716
16th to endNight
9%110%31%45%
1815
October1st to 15thNight
19%2314%31%26%
1815
16th to endNight
19%238%24%41%
2126
November1st to 15thNight
18%25%13%29%30%
2275
16th to endNight
24%3414%20%32%
2340
December1st to 15thNight
30%46%14%20%23%
2340
16th to endNight
32%37%13%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
28%10%34%24%2
90
16th to endDay
16%16%34%28%31
261
February1st to 15thDay
8%21%31%30%8%
266
16th to endDay
18%27%29%21%3
238
March1st to 15thDay
10%18%35%25%7%2
270
16th to endDay
10%19%40%19%8%1
288
April1st to 15thDay
12%26%37%16%5%1
234
16th to endDay
10%27%40%18%2
210
May1st to 15thDay
11%20%37%27%2
228
16th to endDay
10%15%42%24%5%
266
June1st to 15thDay
310%47%32%4
255
16th to endDay
35%34%44%10%2
255
July1st to 15thDay
2230%53%8%2
245
16th to endDay
4119%57%15%2
271
August1st to 15thDay
1332%48%9%3
255
16th to endDay
2125%54%11%4
268
September1st to 15thDay
25%42%38%9%
255
16th to endDay
19%40%39%8%1
255
October1st to 15thDay
7%13%43%28%6%
255
16th to endDay
7%7%32%37%13%1
198
November1st to 15thDay
411%23%27%31%2
90
16th to endDay
10%15%32%31%11%
90
December1st to 15thDay
27%36%41%12%
90
16th to endDay
12%16%34%32%4
96
January1st to 15thNight
8%5%29%33%18%5%
720
16th to endNight
13%327%33%18%3
768
February1st to 15thNight
10%427%33%20%3
704
16th to endNight
16%7%29%30%12%4
632
March1st to 15thNight
8%8%29%33%16%3
720
16th to endNight
7%7%29%33%18%3
768
April1st to 15thNight
11%11%32%28%12%2
687
16th to endNight
9%9%33%27%16%4
660
May1st to 15thNight
6%7%28%42%12%1
514
16th to endNight
5%8%31%37%15%1
515
June1st to 15thNight
3429%46%14%1
495
16th to endNight
122%58%16%
495
July1st to 15thNight
28%54%32%1
465
16th to endNight
29%50%35%1
549
August1st to 15thNight
17%45%41%3
657
16th to endNight
25%36%45%9%
700
September1st to 15thNight
19%34%44%9%
660
16th to endNight
1214%36%37%7%
656
October1st to 15thNight
5%423%35%25%5%
660
16th to endNight
5%416%34%26%11%
704
November1st to 15thNight
4320%37%27%6%
700
16th to endNight
8%421%33%25%7%
720
December1st to 15thNight
10%5%26%33%19%3
720
16th to endNight
14%6%30%27%16%3
768
Page generated at 2017-04-08 02:35:17. Version ac04

Copyright 2017 A. Danko


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