Sights Above Private Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sights Above Private Observatory clear sky chart from 2005-11-05 to 2017-03-14.

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
27%
14414
18%
45154
8%
14382
39%
14382
20%
29492

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%
720
20%
2506
7%
716
33%
716
16%
1583
January16th to endNight
17%
768
21%
2667
5%
768
37%
768
15%
1688
February1st to 15thNight
13%
704
18%
2180
4%
701
29%
701
16%
1455
February16th to endNight
16%
631
24%
1893
7%
631
36%
631
19%
1237
March1st to 15thNight
18%
716
17%
2147
5%
716
32%
716
17%
1455
March16th to endNight
19%
704
22%
1840
6%
704
32%
704
22%
1226
April1st to 15thNight
19%
658
17%
1646
4%
658
26%
658
19%
1198
April16th to endNight
23%
590
17%
1580
4%
590
32%
590
22%
1075
May1st to 15thNight
24%
495
17%
1485
7%
495
33%
495
18%
1024
May16th to endNight
33%
353
12%
1379
9%
352
40%
352
17%
882
June1st to 15thNight
30%
330
13%
1320
9%
330
42%
330
15%
895
June16th to endNight
46%
330
13%
1320
12%
330
55%
330
24%
766
July1st to 15thNight
39%
310
12%
1240
13%
310
44%
310
20%
773
July16th to endNight
50%
348
13%
1306
14%
326
55%
326
22%
796
August1st to 15thNight
43%
468
17%
1449
10%
466
48%
466
27%
892
August16th to endNight
51%
700
17%
1750
9%
700
54%
700
31%
1165
September1st to 15thNight
40%
660
22%
1677
10%
660
46%
660
30%
1110
September16th to endNight
46%
657
24%
1815
18%
657
51%
657
31%
1152
October1st to 15thNight
34%
660
22%
1875
11%
660
45%
660
25%
1232
October16th to endNight
25%
704
16%
2249
6%
704
38%
704
21%
1462
November1st to 15thNight
28%
700
20%
2277
9%
700
44%
700
22%
1432
November16th to endNight
24%
720
20%
2345
9%
720
38%
720
19%
1520
December1st to 15thNight
21%
720
16%
2520
6%
720
35%
720
15%
1662
December16th to endNight
15%
768
18%
2688
4%
768
33%
768
14%
1812

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
17%5%25%42445%6%40%
45561
Night
17%6%24424446%41%
45324
Cloud CoverDay
17%6%2442445%7%40%
45571
Night
17%6%25%424446%41%
45329
TransparencyDay
43%6%12%21%14%2
45249
Night
43%5%12%21%15%2
45154
SeeingDay
20%14%30%21%10%2
5116
Night
21%14%32%24%7%
14414

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
15%7%244245%6%5%41%
1432
16th to endDay
15%7%3442345%5%42%
1554
February1st to 15thDay
17%6%25%5%35%45%6%36%
1681
16th to endDay
17%6%345%35%446%38%
1580
March1st to 15thDay
19%6%245%33447%37%
1775
16th to endDay
17%6%35%423335%42%
2028
April1st to 15thDay
20%7%24423346%39%
1972
16th to endDay
17%414424346%45%
2049
May1st to 15thDay
24%6%25%413337%36%
2137
16th to endDay
17%5%2442435%8%40%
2393
June1st to 15thDay
24%5%25%5%2445%7%32%
2310
16th to endDay
14%5%245%35%5%6%9%38%
2310
July1st to 15thDay
12%5%25%5%36%5%5%7%38%
2310
16th to endDay
13%5%25%5%25%6%6%8%37%
2458
August1st to 15thDay
14%5%25%5%35%5%7%8%37%
2157
16th to endDay
12%5%36%5%345%6%7%41%
2100
September1st to 15thDay
14%5%24424446%46%
1953
16th to endDay
16%423323446%47%
1815
October1st to 15thDay
19%6%24423445%42%
1754
16th to endDay
16%5%24433446%42%
1622
November1st to 15thDay
18%6%24433335%44%
1581
16th to endDay
16%5%25%334346%43%
1614
December1st to 15thDay
18%7%25%5%24336%40%
1440
16th to endDay
21%8%25%324345%36%
1536
January1st to 15thNight
18%7%2442335%6%41%
2506
16th to endNight
16%8%35%323336%42%
2667
February1st to 15thNight
14%9%346%24346%39%
2179
16th to endNight
17%6%24433445%41%
1893
March1st to 15thNight
19%6%25%42345%6%38%
2134
16th to endNight
17%7%34313336%45%
1840
April1st to 15thNight
19%6%45%43444438%
1646
16th to endNight
20%435%5%23336%41%
1580
May1st to 15thNight
19%7%25%425%447%36%
1485
16th to endNight
18%425%32445%8%38%
1377
June1st to 15thNight
22%425%5%34347%36%
1320
16th to endNight
12%5%235%1436%8%45%
1320
July1st to 15thNight
12%6%245%45%5%6%8%37%
1320
16th to endNight
11%425%6%35%5%7%9%36%
1402
August1st to 15thNight
10%5%244347%6%8%42%
1459
16th to endNight
12%5%24445%446%45%
1750
September1st to 15thNight
14%5%24434446%45%
1677
16th to endNight
15%5%2442443449%
1815
October1st to 15thNight
17%5%15%424345%45%
1875
16th to endNight
19%6%25%423446%40%
2249
November1st to 15thNight
18%6%24323435%44%
2277
16th to endNight
20%5%25%334345%40%
2345
December1st to 15thNight
20%7%34424445%38%
2520
16th to endNight
21%7%2443445%5%36%
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
16%7%2433445%442%
1432
16th to endDay
16%6%25%42435%6%41%
1554
February1st to 15thDay
16%6%25%5%35%447%37%
1681
16th to endDay
17%6%25%5%35%446%38%
1580
March1st to 15thDay
20%5%345%24347%37%
1785
16th to endDay
17%6%35%43433442%
2028
April1st to 15thDay
21%6%33424346%39%
1972
16th to endDay
17%413424347%45%
2049
May1st to 15thDay
24%6%24323346%36%
2137
16th to endDay
17%425%42435%8%40%
2393
June1st to 15thDay
24%5%25%5%2445%7%32%
2310
16th to endDay
12%6%26%4345%5%10%37%
2310
July1st to 15thDay
14%5%35%5%35%5%5%9%37%
2310
16th to endDay
13%5%24435%6%6%8%38%
2458
August1st to 15thDay
13%5%246%35%5%6%8%37%
2157
16th to endDay
11%5%26%6%2446%8%40%
2100
September1st to 15thDay
14%5%1442445%6%44%
1953
16th to endDay
16%5%1342435%6%47%
1815
October1st to 15thDay
19%6%245%2344442%
1754
16th to endDay
16%5%2442445%6%42%
1622
November1st to 15thDay
18%7%24424235%44%
1581
16th to endDay
16%434423447%43%
1614
December1st to 15thDay
19%5%25%5%23446%40%
1440
16th to endDay
22%8%25%423346%36%
1536
January1st to 15thNight
18%7%15%323346%42%
2506
16th to endNight
17%8%35%323436%42%
2667
February1st to 15thNight
15%8%35%6%2335%6%40%
2172
16th to endNight
18%6%2442435%5%42%
1893
March1st to 15thNight
20%6%25%324446%38%
2147
16th to endNight
17%7%25%322335%44%
1839
April1st to 15thNight
19%7%35%5%14445%38%
1646
16th to endNight
20%5%25%432335%41%
1580
May1st to 15thNight
20%6%343345%47%36%
1485
16th to endNight
18%5%2442445%9%37%
1377
June1st to 15thNight
22%6%25%33435%6%35%
1320
16th to endNight
13%5%2432346%9%44%
1320
July1st to 15thNight
12%5%35%425%5%7%8%37%
1320
16th to endNight
12%425%6%46%47%9%35%
1402
August1st to 15thNight
10%5%145%35%6%7%7%42%
1459
16th to endNight
12%425%5%45%447%43%
1750
September1st to 15thNight
14%6%2442445%6%44%
1677
16th to endNight
15%5%25%32433448%
1815
October1st to 15thNight
17%5%25%5%13435%44%
1875
16th to endNight
18%6%25%424346%40%
2249
November1st to 15thNight
18%5%24323245%44%
2277
16th to endNight
19%6%3443335%5%40%
2345
December1st to 15thNight
21%6%24433346%38%
2520
16th to endNight
21%7%25%42445%5%36%
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
42%6%14%22%11%3
1433
16th to endDay
41%5%11%25%13%2
1554
February1st to 15thDay
46%6%13%19%13%1
1684
16th to endDay
44%5%11%23%12%2
1580
March1st to 15thDay
47%413%22%9%2
1785
16th to endDay
44%410%19%17%3
2028
April1st to 15thDay
45%5%10%19%15%3
1972
16th to endDay
38%5%9%22%19%4
2049
May1st to 15thDay
48%5%9%20%13%2
2137
16th to endDay
41%8%15%18%14%2
2397
June1st to 15thDay
50%7%12%18%9%1
2310
16th to endDay
40%9%14%22%12%1
2310
July1st to 15thDay
43%6%11%21%14%1
2161
16th to endDay
39%8%15%20%13%2
2291
August1st to 15thDay
41%8%13%20%15%
2143
16th to endDay
39%6%10%24%17%1
2100
September1st to 15thDay
39%6%13%19%20%1
1953
16th to endDay
36%5%7%23%25%2
1815
October1st to 15thDay
43%5%11%21%16%2
1754
16th to endDay
41%5%11%24%15%2
1622
November1st to 15thDay
44%412%18%17%2
1581
16th to endDay
41%411%25%14%2
1614
December1st to 15thDay
45%415%18%14%1
1440
16th to endDay
49%5%14%18%11%
1536
January1st to 15thNight
43%413%22%13%2
2506
16th to endNight
43%410%22%16%2
2667
February1st to 15thNight
45%5%12%21%11%2
2180
16th to endNight
43%410%22%16%2
1893
March1st to 15thNight
45%6%13%19%12%3
2147
16th to endNight
42%39%21%18%4
1840
April1st to 15thNight
48%5%10%18%14%2
1646
16th to endNight
45%48%21%17%4
1580
May1st to 15thNight
46%6%11%17%14%3
1485
16th to endNight
43%8%17%16%12%1
1379
June1st to 15thNight
49%6%12%17%12%1
1320
16th to endNight
35%7%15%26%14%
1320
July1st to 15thNight
41%7%13%21%14%
1240
16th to endNight
39%7%16%23%10%2
1306
August1st to 15thNight
36%7%15%23%15%2
1449
16th to endNight
39%5%10%27%15%
1750
September1st to 15thNight
39%5%11%24%18%
1677
16th to endNight
38%46%22%26%1
1815
October1st to 15thNight
42%5%10%21%17%3
1875
16th to endNight
44%414%21%14%
2249
November1st to 15thNight
41%412%19%18%3
2277
16th to endNight
45%311%24%12%2
2345
December1st to 15thNight
47%414%19%12%
2520
16th to endNight
49%412%19%12%
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
21%28%31%16%1
60
16th to endDay
26%23%40%8%
67
February1st to 15thDay
23%23%35%15%2
197
16th to endDay
18%25%36%14%4
239
March1st to 15thDay
25%23%31%17%3
264
16th to endDay
19%24%33%15%42
224
April1st to 15thDay
28%18%30%16%6%
210
16th to endDay
15%15%36%19%10%3
210
May1st to 15thDay
35%12%25%14%9%2
228
16th to endDay
17%15%29%25%11%1
267
June1st to 15thDay
25%16%24%20%10%2
255
16th to endDay
14%11%32%29%10%1
255
July1st to 15thDay
18%6%27%31%14%2
245
16th to endDay
13%5%35%28%12%3
270
August1st to 15thDay
14%6%28%32%13%4
253
16th to endDay
12%5%26%27%18%9%
268
September1st to 15thDay
17%7%27%22%19%5%
255
16th to endDay
17%7%30%16%16%11%
254
October1st to 15thDay
22%9%25%24%14%4
255
16th to endDay
17%19%32%20%8%
247
November1st to 15thDay
22%16%26%22%9%2
235
16th to endDay
20%18%32%19%8%1
234
December1st to 15thDay
18%28%36%10%6%
60
16th to endDay
37%23%26%10%1
64
January1st to 15thNight
24%20%36%15%3
720
16th to endNight
23%21%33%19%1
768
February1st to 15thNight
20%19%40%17%1
704
16th to endNight
22%20%35%18%2
631
March1st to 15thNight
25%19%34%17%2
716
16th to endNight
20%22%34%18%3
704
April1st to 15thNight
22%20%34%19%2
658
16th to endNight
22%15%33%22%5%
590
May1st to 15thNight
21%18%31%22%5%
495
16th to endNight
20%7%33%30%7%
353
June1st to 15thNight
25%6%31%29%6%
330
16th to endNight
14%331%41%9%
330
July1st to 15thNight
14%235%33%13%
310
16th to endNight
13%424%42%13%1
348
August1st to 15thNight
13%432%37%11%
468
16th to endNight
14%323%37%18%2
700
September1st to 15thNight
17%6%30%31%13%1
660
16th to endNight
18%5%23%29%20%3
657
October1st to 15thNight
20%10%30%25%11%1
660
16th to endNight
24%13%34%21%5%
704
November1st to 15thNight
22%15%30%21%8%1
700
16th to endNight
23%16%30%20%7%
720
December1st to 15thNight
26%16%30%20%5%
720
16th to endNight
26%19%35%16%1
768
Page generated at 2017-03-15 11:32:37. Version ac04

Copyright 2017 A. Danko


Sights Above Private Observatory Clear Sky Chart | Charts Home