Bill Sadowski Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bill Sadowski Park clear sky chart from 2005-11-05 to 2017-09-18.

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
57%
16298
16%
46957
13%
16260
61%
16260
23%
31335

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
47%
716
15%
2327
12%
716
53%
716
20%
1496
January16th to endNight
49%
768
23%
2463
19%
768
58%
768
25%
1479
February1st to 15thNight
51%
701
25%
2084
20%
699
57%
699
30%
1243
February16th to endNight
54%
631
30%
1735
17%
631
64%
631
35%
1006
March1st to 15thNight
50%
720
23%
1980
15%
720
57%
720
28%
1238
March16th to endNight
55%
768
23%
2112
18%
768
60%
768
31%
1266
April1st to 15thNight
64%
718
23%
1976
17%
718
69%
718
38%
1112
April16th to endNight
59%
720
23%
1806
13%
720
64%
720
33%
1124
May1st to 15thNight
65%
719
23%
1799
15%
719
67%
719
39%
1036
May16th to endNight
60%
632
13%
1754
11%
632
61%
632
24%
1228
June1st to 15thNight
52%
540
7%
1620
6%
540
53%
540
13%
1253
June16th to endNight
66%
540
6%
1620
6%
540
67%
540
18%
1162
July1st to 15thNight
67%
510
5%
1530
5%
510
68%
510
18%
1118
July16th to endNight
68%
564
10%
1595
9%
531
72%
531
25%
1037
August1st to 15thNight
69%
626
8%
1696
7%
623
70%
623
23%
1189
August16th to endNight
65%
764
6%
2027
5%
764
65%
764
19%
1515
September1st to 15thNight
63%
720
4%
1980
4%
720
63%
720
14%
1567
September16th to endNight
53%
669
5%
1848
3%
669
56%
669
12%
1490
October1st to 15thNight
59%
660
11%
1919
12%
660
60%
660
16%
1426
October16th to endNight
50%
704
16%
2112
14%
704
54%
704
19%
1494
November1st to 15thNight
51%
700
20%
2101
16%
700
56%
700
22%
1414
November16th to endNight
50%
720
21%
2160
16%
720
57%
720
19%
1463
December1st to 15thNight
51%
720
20%
2217
16%
720
57%
720
20%
1490
December16th to endNight
59%
768
21%
2496
20%
768
64%
768
26%
1489

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
8%5%36%7%47%7%8%10%29%
47816
Night
6%425%5%36%6%7%10%39%
47163
TransparencyDay
40%13%18%15%9%2
47518
Night
38%10%18%19%10%2
46965
SeeingDay
8%9%8%21%28%23%
6104
Night
7%15%9%24%28%14%
16308

By Month

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
8%6%36%6%45%6%7%9%33%
1611
16th to endDay
8%435%6%46%6%7%10%36%
1758
February1st to 15thDay
9%425%6%345%6%9%42%
1769
16th to endDay
6%3135%35%6%7%10%44%
1738
March1st to 15thDay
6%4246%36%6%8%11%39%
1980
16th to endDay
5%445%5%45%5%7%10%40%
2111
April1st to 15thDay
5%3245%35%6%8%12%43%
1972
16th to endDay
6%4145%46%7%8%12%37%
2153
May1st to 15thDay
33145%47%7%8%10%41%
2152
16th to endDay
9%5%36%8%5%8%8%10%11%21%
2367
June1st to 15thDay
12%7%5%10%10%6%9%8%6%8%13%
2340
16th to endDay
6%6%48%10%7%10%8%9%11%16%
2340
July1st to 15thDay
6%5%37%9%6%8%9%10%13%19%
2340
16th to endDay
6%427%9%6%8%10%10%12%21%
2465
August1st to 15thDay
5%6%38%9%5%7%9%9%11%23%
2238
16th to endDay
9%5%38%8%5%9%9%10%10%19%
2171
September1st to 15thDay
8%5%38%10%6%9%10%10%9%16%
1980
16th to endDay
11%9%5%9%10%6%9%8%7%8%13%
1837
October1st to 15thDay
8%6%39%8%5%8%7%8%9%22%
1709
16th to endDay
13%6%37%7%36%6%7%8%29%
1760
November1st to 15thDay
8%5%36%5%46%6%7%9%35%
1757
16th to endDay
9%5%26%6%37%6%7%9%35%
1800
December1st to 15thDay
9%6%35%6%37%5%7%9%33%
1740
16th to endDay
6%5%25%6%36%7%10%11%33%
1728
January1st to 15thNight
7%5%25%6%36%6%8%10%36%
2327
16th to endNight
5%424435%46%11%46%
2463
February1st to 15thNight
9%33442346%9%47%
2082
16th to endNight
421442446%10%53%
1735
March1st to 15thNight
5%315%5%35%5%6%8%48%
1980
16th to endNight
4314425%5%6%9%49%
2112
April1st to 15thNight
32134245%6%10%56%
1976
16th to endNight
6%3234246%8%10%47%
1806
May1st to 15thNight
211442447%10%56%
1799
16th to endNight
7%5%36%5%37%6%8%10%34%
1753
June1st to 15thNight
11%7%47%7%47%7%8%11%22%
1620
16th to endNight
5%4246%5%8%8%10%14%29%
1620
July1st to 15thNight
5%435%6%48%8%10%12%30%
1620
16th to endNight
24145%46%7%8%13%39%
1703
August1st to 15thNight
4325%6%47%6%8%14%35%
1707
16th to endNight
6%427%7%5%7%8%10%12%27%
2027
September1st to 15thNight
6%5%37%7%48%9%9%10%26%
1980
16th to endNight
7%7%39%8%47%9%8%11%21%
1848
October1st to 15thNight
7%6%26%8%47%6%9%11%28%
1919
16th to endNight
13%6%37%6%36%5%6%7%33%
2112
November1st to 15thNight
8%426%5%36%6%6%8%41%
2101
16th to endNight
9%5%26%6%36%6%6%9%39%
2160
December1st to 15thNight
10%5%25%5%45%6%7%10%37%
2217
16th to endNight
6%3245%36%5%7%10%45%
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
40%11%15%17%11%3
1612
16th to endDay
36%8%16%17%15%4
1758
February1st to 15thDay
34%5%14%22%18%4
1772
16th to endDay
26%9%17%27%14%4
1738
March1st to 15thDay
29%10%18%22%16%2
1980
16th to endDay
30%10%17%23%14%4
2112
April1st to 15thDay
25%9%21%25%16%1
1972
16th to endDay
30%10%17%21%17%2
2153
May1st to 15thDay
27%11%17%23%14%5%
2152
16th to endDay
43%14%18%18%4
2371
June1st to 15thDay
58%16%14%8%2
2340
16th to endDay
50%19%20%8%1
2340
July1st to 15thDay
44%20%25%8%
2201
16th to endDay
40%21%27%9%
2310
August1st to 15thDay
41%20%23%12%2
2225
16th to endDay
46%21%21%9%
2171
September1st to 15thDay
50%23%18%6%
1980
16th to endDay
54%21%13%7%2
1837
October1st to 15thDay
47%15%16%13%6%
1709
16th to endDay
46%9%14%13%11%4
1760
November1st to 15thDay
41%8%15%14%15%4
1757
16th to endDay
41%8%12%13%19%5%
1800
December1st to 15thDay
41%9%14%17%15%2
1740
16th to endDay
37%10%15%20%14%2
1728
January1st to 15thNight
40%8%17%20%10%3
2327
16th to endNight
32%9%13%24%15%3
2463
February1st to 15thNight
34%5%12%24%17%6%
2090
16th to endNight
26%7%15%26%18%5%
1735
March1st to 15thNight
33%7%11%25%17%4
1980
16th to endNight
29%8%16%24%17%3
2112
April1st to 15thNight
24%6%18%31%16%2
1976
16th to endNight
29%8%18%22%18%3
1806
May1st to 15thNight
23%7%16%33%15%4
1800
16th to endNight
42%9%18%22%7%
1755
June1st to 15thNight
51%13%20%11%3
1620
16th to endNight
39%17%31%11%
1620
July1st to 15thNight
40%19%30%10%
1530
16th to endNight
30%16%34%16%1
1595
August1st to 15thNight
34%18%28%17%1
1696
16th to endNight
43%15%27%12%
2027
September1st to 15thNight
46%21%21%9%1
1980
16th to endNight
53%16%18%8%3
1848
October1st to 15thNight
47%13%16%13%7%1
1919
16th to endNight
48%7%11%18%11%3
2112
November1st to 15thNight
43%7%12%16%17%3
2101
16th to endNight
43%8%10%16%15%5%
2160
December1st to 15thNight
42%8%13%18%13%2
2217
16th to endNight
33%8%14%24%16%2
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
16%325%35%18%
90
16th to endDay
11%9%25%34%15%4
96
February1st to 15thDay
7%7%17%40%24%3
111
16th to endDay
8%11%17%35%25%
239
March1st to 15thDay
6%11%20%38%21%1
270
16th to endDay
6%13%20%32%21%5%
288
April1st to 15thDay
5%12%12%32%31%5%
270
16th to endDay
6%11%6%41%31%2
270
May1st to 15thDay
211%6%29%35%14%
288
16th to endDay
49%314%40%27%
331
June1st to 15thDay
11%10%6%12%31%26%
315
16th to endDay
5%9%16%25%51%
315
July1st to 15thDay
37%431%53%
305
16th to endDay
410%15%27%49%
326
August1st to 15thDay
8%5%6%30%48%
313
16th to endDay
12%4110%26%44%
332
September1st to 15thDay
8%4410%23%48%
315
16th to endDay
15%6%7%25%44%
262
October1st to 15thDay
10%6%322%41%16%
255
16th to endDay
18%8%9%26%28%8%
272
November1st to 15thDay
10%10%13%26%28%10%
265
16th to endDay
10%12%21%30%22%2
270
December1st to 15thDay
15%10%12%30%25%6%
210
16th to endDay
429%36%46%1
96
January1st to 15thNight
9%20%14%28%24%3
720
16th to endNight
7%20%16%35%19%
768
February1st to 15thNight
7%17%17%33%23%
704
16th to endNight
5%17%17%38%20%
631
March1st to 15thNight
6%19%18%32%21%2
720
16th to endNight
5%17%15%35%23%2
768
April1st to 15thNight
316%9%39%28%2
718
16th to endNight
6%17%9%39%25%1
720
May1st to 15thNight
317%6%32%35%4
720
16th to endNight
7%17%316%40%14%
634
June1st to 15thNight
9%16%213%33%23%
540
16th to endNight
416%17%30%39%
540
July1st to 15thNight
5%11%16%31%43%
510
16th to endNight
316%425%48%
564
August1st to 15thNight
6%9%5%38%39%
626
16th to endNight
8%8%48%34%35%
764
September1st to 15thNight
8%8%29%30%39%
720
16th to endNight
10%9%5%11%27%36%
669
October1st to 15thNight
10%10%421%36%15%
660
16th to endNight
16%10%10%23%27%11%
704
November1st to 15thNight
9%15%14%29%24%5%
700
16th to endNight
10%17%12%31%23%4
720
December1st to 15thNight
11%17%12%30%25%2
720
16th to endNight
5%17%12%27%31%5%
768
Page generated at 2017-09-19 07:32:32. Version ac04

Copyright 2017 A. Danko


Bill Sadowski Park Clear Sky Chart | Charts Home