Fox Park Public Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fox Park Public Observatory clear sky chart from 2005-11-05 to

2017-09-12
.

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
37%
15922
15%
46742
10%
15880
41%
15880
20%
33033

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
16%
900
8%
2506
3%
895
20%
895
10%
2062
January16th to endNight
21%
927
6%
2655
3%
927
24%
927
10%
2219
February1st to 15thNight
18%
701
9%
2217
3%
701
24%
701
10%
1750
February16th to endNight
23%
631
13%
1893
6%
631
30%
631
14%
1432
March1st to 15thNight
30%
720
15%
2112
10%
720
34%
720
18%
1507
March16th to endNight
32%
765
18%
2109
10%
765
39%
765
22%
1491
April1st to 15thNight
26%
539
12%
1797
8%
539
32%
539
18%
1232
April16th to endNight
34%
540
19%
1620
9%
540
42%
540
24%
1066
May1st to 15thNight
35%
540
14%
1620
7%
540
42%
540
21%
1136
May16th to endNight
47%
562
15%
1606
11%
561
51%
561
29%
1023
June1st to 15thNight
54%
540
15%
1440
10%
540
58%
540
34%
908
June16th to endNight
57%
540
15%
1440
11%
540
60%
540
33%
915
July1st to 15thNight
66%
510
17%
1360
14%
510
68%
510
41%
812
July16th to endNight
68%
564
20%
1445
17%
531
70%
531
41%
848
August1st to 15thNight
66%
539
21%
1609
18%
536
69%
536
36%
933
August16th to endNight
61%
573
21%
1793
18%
573
65%
573
33%
1040
September1st to 15thNight
60%
620
26%
1857
22%
620
64%
620
35%
1079
September16th to endNight
57%
657
22%
1815
17%
657
60%
657
33%
1133
October1st to 15thNight
46%
660
21%
1864
16%
660
51%
660
26%
1243
October16th to endNight
27%
704
15%
2250
9%
704
36%
704
17%
1605
November1st to 15thNight
37%
700
19%
2276
17%
700
42%
700
20%
1521
November16th to endNight
27%
720
13%
2340
9%
720
32%
720
13%
1762
December1st to 15thNight
17%
810
6%
2430
2%
810
21%
810
10%
1986
December16th to endNight
14%
960
7%
2688
1%
960
19%
960
7%
2330

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
14%8%47%6%35%45%7%33%
47924
Night
15%9%46%5%34446%34%
46914
Cloud CoverDay
13%9%47%6%35%45%7%33%
47933
Night
14%9%46%5%3445%6%34%
46919
TransparencyDay
49%6%11%19%10%1
47614
Night
49%6%11%19%11%1
46742
SeeingDay
16%7%26%25%16%7%
5918
Night
19%7%28%30%12%1
15926

By Month

Percentage Cloud Cover NE (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
17%15%7%10%8%45%5%45%14%
1432
16th to endDay
13%18%8%11%9%45%345%13%
1567
February1st to 15thDay
13%15%6%11%9%45%435%20%
1642
16th to endDay
14%13%6%11%6%26%5%45%21%
1580
March1st to 15thDay
14%11%47%7%2446%7%28%
1838
16th to endDay
17%10%47%5%2335%7%31%
2127
April1st to 15thDay
19%12%35%5%34345%31%
2151
16th to endDay
16%7%35%5%35%446%38%
2340
May1st to 15thDay
19%6%37%6%34447%33%
2331
16th to endDay
13%6%35%435%45%7%39%
2506
June1st to 15thDay
10%425%5%45%5%6%7%42%
2520
16th to endDay
9%336%6%36%6%7%10%37%
2520
July1st to 15thDay
7%4245%35%5%6%10%45%
2520
16th to endDay
7%425%5%35%6%6%9%42%
2625
August1st to 15thDay
9%425%6%35%5%6%8%41%
2340
16th to endDay
11%5%35%5%35%5%6%8%39%
2408
September1st to 15thDay
12%5%245%4445%7%42%
2011
16th to endDay
12%5%25%6%35%46%8%39%
1815
October1st to 15thDay
15%6%36%6%34446%39%
1766
16th to endDay
22%9%45%5%35%446%29%
1620
November1st to 15thDay
14%10%246%33446%38%
1582
16th to endDay
17%15%47%7%34436%25%
1620
December1st to 15thDay
14%14%9%12%6%34345%19%
1527
16th to endDay
19%18%8%10%6%3434415%
1536
January1st to 15thNight
20%14%6%10%7%3433420%
2506
16th to endNight
12%14%9%12%8%5%5%45%6%16%
2655
February1st to 15thNight
15%15%6%8%7%45%5%3423%
2215
16th to endNight
14%11%5%8%7%35%45%7%25%
1893
March1st to 15thNight
15%10%46%6%24447%34%
2099
16th to endNight
15%7%46%435%5%47%35%
2109
April1st to 15thNight
19%7%45%6%24446%34%
1797
16th to endNight
17%7%24434446%39%
1620
May1st to 15thNight
19%5%25%5%245%47%34%
1620
16th to endNight
12%6%25%43345%9%43%
1604
June1st to 15thNight
12%4245%3336%7%47%
1440
16th to endNight
8%415%425%5%6%11%43%
1440
July1st to 15thNight
7%3144245%5%10%51%
1440
16th to endNight
6%32332446%9%52%
1543
August1st to 15thNight
6%3145%345%6%8%50%
1620
16th to endNight
10%5%25%423447%50%
1793
September1st to 15thNight
12%313324346%52%
1857
16th to endNight
10%435%424448%46%
1815
October1st to 15thNight
17%5%2443345%6%41%
1864
16th to endNight
21%8%26%5%34345%32%
2250
November1st to 15thNight
16%9%35%424445%38%
2276
16th to endNight
18%15%46%434445%27%
2340
December1st to 15thNight
19%16%6%8%7%33445%19%
2430
16th to endNight
22%15%8%11%6%35%435%13%
2688

Percentage Cloud Cover SE (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
17%15%7%9%9%45%5%46%14%
1432
16th to endDay
14%18%8%10%10%35%34414%
1567
February1st to 15thDay
13%14%6%11%9%5%5%43420%
1642
16th to endDay
14%13%6%12%6%36%5%5%421%
1580
March1st to 15thDay
14%10%5%8%6%3445%7%28%
1848
16th to endDay
17%10%47%5%3335%7%31%
2126
April1st to 15thDay
19%12%36%5%34436%30%
2151
16th to endDay
16%7%26%5%35%447%37%
2340
May1st to 15thDay
18%7%36%5%34447%33%
2331
16th to endDay
12%6%35%5%35%45%7%39%
2506
June1st to 15thDay
10%5%25%6%35%5%5%7%42%
2520
16th to endDay
9%426%6%35%7%7%9%37%
2520
July1st to 15thDay
7%4145%346%6%9%45%
2520
16th to endDay
7%5%25%435%6%7%9%42%
2625
August1st to 15thDay
8%5%25%6%45%5%6%9%40%
2340
16th to endDay
11%5%25%5%345%6%8%39%
2408
September1st to 15thDay
12%5%245%35%46%7%42%
2011
16th to endDay
11%5%26%5%25%5%6%8%39%
1815
October1st to 15thDay
14%7%36%5%34446%38%
1766
16th to endDay
21%10%35%5%345%36%29%
1620
November1st to 15thDay
14%9%35%6%33436%38%
1582
16th to endDay
16%15%5%8%6%34446%25%
1620
December1st to 15thDay
15%14%9%12%7%34436%18%
1527
16th to endDay
20%18%8%11%5%3434415%
1536
January1st to 15thNight
20%14%6%9%8%3434419%
2506
16th to endNight
12%14%9%11%8%5%5%45%6%17%
2655
February1st to 15thNight
14%15%5%9%7%45%44324%
2208
16th to endNight
14%10%6%7%8%36%45%7%25%
1893
March1st to 15thNight
15%9%5%7%5%24446%34%
2112
16th to endNight
14%8%36%425%5%47%35%
2109
April1st to 15thNight
19%7%45%5%345%46%34%
1797
16th to endNight
17%7%3443435%6%39%
1620
May1st to 15thNight
19%6%25%6%3445%7%34%
1619
16th to endNight
11%6%25%42445%9%43%
1604
June1st to 15thNight
12%42443335%7%47%
1440
16th to endNight
8%3245%245%7%10%43%
1440
July1st to 15thNight
7%41342346%9%51%
1440
16th to endNight
6%32342446%9%53%
1543
August1st to 15thNight
5%4245%3447%8%49%
1620
16th to endNight
9%4245%2335%7%50%
1793
September1st to 15thNight
11%413423437%52%
1857
16th to endNight
10%5%35%5%24448%46%
1815
October1st to 15thNight
16%6%35%43345%6%41%
1864
16th to endNight
21%8%36%5%34345%32%
2250
November1st to 15thNight
15%9%36%424445%38%
2276
16th to endNight
18%13%5%7%5%34445%27%
2340
December1st to 15thNight
19%15%7%9%7%24435%20%
2430
16th to endNight
21%15%7%11%7%35%34413%
2688

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
71%6%9%9%2
1433
16th to endDay
73%5%8%8%3
1567
February1st to 15thDay
68%5%7%13%4
1644
16th to endDay
64%6%9%13%5%
1580
March1st to 15thDay
53%6%14%16%7%
1848
16th to endDay
52%411%20%8%1
2127
April1st to 15thDay
55%49%19%11%
2151
16th to endDay
45%6%12%17%14%3
2340
May1st to 15thDay
50%6%11%20%9%1
2331
16th to endDay
43%6%12%25%11%1
2510
June1st to 15thDay
38%7%12%24%15%1
2520
16th to endDay
40%8%13%20%16%1
2520
July1st to 15thDay
33%7%12%24%19%3
2371
16th to endDay
35%7%14%24%15%2
2460
August1st to 15thDay
38%7%13%25%12%2
2327
16th to endDay
39%7%11%24%14%2
2408
September1st to 15thDay
39%6%11%25%15%1
2011
16th to endDay
41%5%12%27%13%
1815
October1st to 15thDay
45%5%10%23%13%1
1766
16th to endDay
55%6%12%18%6%
1620
November1st to 15thDay
46%5%11%21%12%1
1582
16th to endDay
60%5%12%15%4
1620
December1st to 15thDay
67%5%11%11%3
1527
16th to endDay
73%49%8%2
1536
January1st to 15thNight
67%410%11%5%
2506
16th to endNight
67%6%12%9%3
2655
February1st to 15thNight
63%5%9%14%5%
2217
16th to endNight
57%6%12%16%6%1
1893
March1st to 15thNight
51%5%11%19%9%1
2112
16th to endNight
47%6%11%22%10%1
2109
April1st to 15thNight
49%5%11%18%14%
1797
16th to endNight
44%5%12%18%15%3
1620
May1st to 15thNight
47%6%10%20%11%2
1620
16th to endNight
38%6%13%23%15%2
1606
June1st to 15thNight
34%6%13%28%16%1
1440
16th to endNight
33%9%16%23%16%1
1440
July1st to 15thNight
28%6%12%29%20%2
1360
16th to endNight
26%7%15%25%21%2
1445
August1st to 15thNight
29%7%13%29%17%2
1609
16th to endNight
33%5%11%27%19%3
1793
September1st to 15thNight
31%5%10%29%21%1
1857
16th to endNight
35%5%12%27%17%
1815
October1st to 15thNight
43%5%10%23%16%1
1864
16th to endNight
53%411%22%8%
2250
November1st to 15thNight
46%5%11%21%12%1
2276
16th to endNight
57%6%11%18%5%
2340
December1st to 15thNight
66%6%11%10%5%
2430
16th to endNight
73%5%9%8%2
2688

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
16%13%47%16%5%
90
16th to endDay
30%8%40%17%21
96
February1st to 15thDay
22%16%50%11%
90
16th to endDay
18%18%33%22%7%
81
March1st to 15thDay
27%10%34%20%7%
138
16th to endDay
26%6%27%26%10%2
288
April1st to 15thDay
24%8%30%27%7%2
270
16th to endDay
20%8%31%20%13%5%
270
May1st to 15thDay
23%9%26%23%11%5%
288
16th to endDay
17%7%27%24%15%6%
406
June1st to 15thDay
14%428%31%14%6%
495
16th to endDay
12%6%30%29%13%6%
495
July1st to 15thDay
8%422%30%23%10%
475
16th to endDay
9%223%30%23%10%
485
August1st to 15thDay
10%115%27%22%22%
313
16th to endDay
14%317%20%28%16%
332
September1st to 15thDay
13%316%24%25%16%
299
16th to endDay
15%414%25%27%12%
254
October1st to 15thDay
16%8%20%32%18%4
255
16th to endDay
25%10%32%25%5%
132
November1st to 15thDay
6%13%27%36%11%4
90
16th to endDay
28%16%36%10%7%
90
December1st to 15thDay
24%23%36%12%3
90
16th to endDay
27%30%38%31
96
January1st to 15thNight
26%12%34%18%5%1
900
16th to endNight
17%11%34%30%5%
927
February1st to 15thNight
22%12%38%22%3
704
16th to endNight
20%11%36%26%5%
631
March1st to 15thNight
20%11%31%28%6%
720
16th to endNight
17%9%34%27%9%1
765
April1st to 15thNight
21%9%35%25%6%
539
16th to endNight
21%6%35%25%10%1
540
May1st to 15thNight
22%431%31%8%1
540
16th to endNight
13%329%34%17%1
563
June1st to 15thNight
13%223%43%15%
540
16th to endNight
10%222%41%21%1
540
July1st to 15thNight
10%115%44%25%3
510
16th to endNight
7%116%43%28%2
564
August1st to 15thNight
7%15%45%26%4
539
16th to endNight
11%118%35%28%5%
573
September1st to 15thNight
14%217%34%26%4
620
16th to endNight
14%417%29%28%4
657
October1st to 15thNight
20%423%32%17%2
660
16th to endNight
24%10%32%24%7%
704
November1st to 15thNight
20%9%28%30%10%1
700
16th to endNight
24%12%30%25%6%
720
December1st to 15thNight
27%11%34%22%4
810
16th to endNight
29%10%35%21%2
960
Page generated at 2017-09-13 07:39:17. Version ac04

Copyright 2017 A. Danko


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