Indian Hill Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Indian Hill Observatory clear sky chart from 2005-11-05 to 2017-12-20.

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
31%
15486
13%
48144
9%
15446
36%
15446
16%
34993

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
8%
718
7%
2327
2%
716
14%
716
6%
1977
January16th to endNight
11%
768
6%
2496
2%
768
15%
768
6%
2122
February1st to 15thNight
12%
703
6%
2287
3%
701
16%
701
7%
1910
February16th to endNight
13%
631
9%
1940
2%
631
19%
631
9%
1561
March1st to 15thNight
20%
720
12%
2001
7%
720
25%
720
12%
1565
March16th to endNight
26%
768
15%
2112
9%
768
32%
768
18%
1545
April1st to 15thNight
22%
704
12%
1863
4%
704
26%
704
17%
1383
April16th to endNight
31%
540
18%
1620
7%
540
40%
540
23%
1098
May1st to 15thNight
38%
540
12%
1620
8%
540
43%
540
19%
1150
May16th to endNight
47%
486
15%
1609
13%
486
50%
486
25%
1003
June1st to 15thNight
47%
360
15%
1440
16%
360
55%
360
21%
868
June16th to endNight
50%
360
16%
1440
17%
360
57%
360
22%
855
July1st to 15thNight
59%
453
15%
1473
15%
453
62%
453
30%
885
July16th to endNight
63%
564
16%
1595
14%
531
65%
531
32%
950
August1st to 15thNight
63%
539
18%
1609
15%
536
64%
536
33%
962
August16th to endNight
61%
599
22%
1745
16%
599
65%
599
33%
1052
September1st to 15thNight
56%
720
21%
1896
14%
720
57%
720
30%
1237
September16th to endNight
51%
717
22%
1980
16%
717
55%
717
28%
1316
October1st to 15thNight
41%
720
17%
2134
15%
720
45%
720
24%
1418
October16th to endNight
21%
768
14%
2304
8%
768
29%
768
15%
1691
November1st to 15thNight
30%
760
16%
2459
13%
760
36%
760
18%
1694
November16th to endNight
15%
780
10%
2724
6%
780
21%
780
9%
2106
December1st to 15thNight
13%
780
5%
2730
3%
780
16%
780
6%
2267
December16th to endNight
8%
788
4%
2740
0%
788
12%
788
5%
2378

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
16%10%47%5%3445%6%29%
48677
Night
15%11%47%6%3445%6%30%
48337
Cloud CoverDay
16%10%47%6%3445%6%29%
48687
Night
15%10%47%6%3445%6%30%
48341
TransparencyDay
53%6%11%17%9%1
48388
Night
53%6%11%17%10%1
48144
SeeingDay
20%14%27%20%12%4
5638
Night
21%14%27%23%11%1
15491

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
19%17%8%10%7%335%4415%
1611
16th to endDay
14%19%12%14%8%3324410%
1728
February1st to 15thDay
14%19%10%12%9%3433315%
1575
16th to endDay
14%18%7%11%7%3444419%
1533
March1st to 15thDay
20%15%7%8%5%23245%23%
1948
16th to endDay
18%11%5%6%424446%29%
2112
April1st to 15thDay
20%12%46%324446%28%
2095
16th to endDay
19%10%35%423345%37%
2340
May1st to 15thDay
18%8%26%6%36%5%47%29%
2331
16th to endDay
13%6%25%5%345%6%8%38%
2506
June1st to 15thDay
15%7%25%5%345%5%7%37%
2520
16th to endDay
14%5%25%5%35%46%10%36%
2520
July1st to 15thDay
11%5%26%5%45%5%6%8%38%
2394
16th to endDay
11%5%25%5%345%6%10%38%
2465
August1st to 15thDay
8%5%26%6%46%6%7%9%35%
2340
16th to endDay
11%6%25%6%35%6%6%8%36%
2444
September1st to 15thDay
16%7%36%4345%6%6%35%
2061
16th to endDay
16%7%26%5%2436%6%37%
1980
October1st to 15thDay
20%7%26%6%25%447%32%
1825
16th to endDay
25%10%36%5%33345%27%
1920
November1st to 15thDay
13%15%47%5%34446%31%
1726
16th to endDay
18%19%6%9%5%24346%19%
1563
December1st to 15thDay
19%18%10%13%6%35%33313%
1560
16th to endDay
17%23%9%14%7%2433210%
1580
January1st to 15thNight
20%18%8%13%6%3333414%
2327
16th to endNight
14%18%9%12%10%3433414%
2496
February1st to 15thNight
17%14%7%13%8%46%43316%
2285
16th to endNight
17%13%6%11%8%3443422%
1940
March1st to 15thNight
18%13%5%10%6%3445%5%25%
1989
16th to endNight
15%10%6%7%5%25%44433%
2112
April1st to 15thNight
18%13%45%5%2345%5%30%
1863
16th to endNight
11%8%37%426%45%6%38%
1620
May1st to 15thNight
16%8%36%6%35%5%5%7%31%
1620
16th to endNight
12%5%25%435%46%9%39%
1607
June1st to 15thNight
8%7%26%6%35%446%42%
1440
16th to endNight
9%437%4346%6%9%40%
1440
July1st to 15thNight
7%425%4345%5%8%47%
1563
16th to endNight
6%434435%5%5%10%46%
1703
August1st to 15thNight
7%415%5%26%5%6%8%46%
1620
16th to endNight
9%5%1443446%8%46%
1745
September1st to 15thNight
14%5%233335%6%6%44%
1896
16th to endNight
14%5%25%5%3445%6%42%
1980
October1st to 15thNight
15%6%25%5%3445%6%39%
2134
16th to endNight
23%8%46%43445%7%27%
2304
November1st to 15thNight
16%10%36%6%3345%6%32%
2459
16th to endNight
19%15%5%8%6%25%35%5%20%
2724
December1st to 15thNight
19%18%8%9%6%35%43416%
2730
16th to endNight
20%19%7%10%7%4444410%
2740

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
19%17%7%11%6%345%4416%
1611
16th to endDay
14%19%11%14%8%4334311%
1728
February1st to 15thDay
14%18%10%11%9%4433315%
1575
16th to endDay
14%17%8%10%6%25%435%19%
1533
March1st to 15thDay
20%15%6%7%5%23346%23%
1959
16th to endDay
18%10%6%6%434446%29%
2111
April1st to 15thDay
20%12%46%5%2435%6%29%
2095
16th to endDay
19%10%25%433336%37%
2340
May1st to 15thDay
18%8%36%5%36%5%5%6%30%
2331
16th to endDay
13%6%25%5%35%47%7%38%
2506
June1st to 15thDay
14%7%35%425%5%6%7%37%
2520
16th to endDay
14%425%5%35%5%5%10%36%
2520
July1st to 15thDay
10%5%35%6%35%5%6%8%37%
2394
16th to endDay
11%5%25%5%45%5%6%10%37%
2465
August1st to 15thDay
8%5%26%7%45%7%7%9%35%
2340
16th to endDay
12%5%25%5%45%5%7%8%36%
2444
September1st to 15thDay
17%6%35%5%35%5%5%6%35%
2061
16th to endDay
16%6%36%434447%37%
1980
October1st to 15thDay
21%6%36%6%25%446%33%
1825
16th to endDay
25%9%27%5%34345%27%
1920
November1st to 15thDay
13%14%47%5%35%446%31%
1726
16th to endDay
18%17%5%10%7%24346%20%
1563
December1st to 15thDay
19%18%10%11%6%3443314%
1560
16th to endDay
17%23%9%13%7%3343310%
1580
January1st to 15thNight
20%17%8%12%6%3433415%
2327
16th to endNight
14%18%8%13%10%3433414%
2496
February1st to 15thNight
15%15%6%14%8%45%44416%
2278
16th to endNight
16%14%5%11%8%35%34422%
1940
March1st to 15thNight
17%12%5%9%5%3444425%
2001
16th to endNight
14%10%5%7%5%345%45%33%
2112
April1st to 15thNight
18%12%46%423345%31%
1863
16th to endNight
11%8%26%5%26%45%6%38%
1620
May1st to 15thNight
16%7%37%5%36%6%5%7%31%
1619
16th to endNight
12%5%25%5%35%36%10%39%
1607
June1st to 15thNight
8%6%27%5%45%5%47%43%
1440
16th to endNight
9%436%5%345%6%9%41%
1440
July1st to 15thNight
6%4246%345%6%8%47%
1563
16th to endNight
6%325%5%35%46%9%47%
1703
August1st to 15thNight
7%415%6%345%6%8%46%
1620
16th to endNight
9%42443446%8%46%
1745
September1st to 15thNight
14%5%244235%5%6%45%
1896
16th to endNight
14%5%245%25%45%6%42%
1980
October1st to 15thNight
15%7%25%5%33447%39%
2134
16th to endNight
22%7%36%6%3446%6%28%
2304
November1st to 15thNight
15%9%37%6%3445%6%33%
2459
16th to endNight
19%14%5%8%6%34446%21%
2724
December1st to 15thNight
19%17%8%9%6%35%34417%
2730
16th to endNight
20%18%7%10%7%45%345%11%
2740

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
70%5%11%8%4
1612
16th to endDay
76%410%6%1
1728
February1st to 15thDay
74%5%7%9%3
1577
16th to endDay
65%6%11%10%5%
1533
March1st to 15thDay
62%5%11%15%4
1959
16th to endDay
55%5%9%19%8%1
2112
April1st to 15thDay
55%5%12%15%11%
2095
16th to endDay
50%410%18%12%3
2340
May1st to 15thDay
52%7%10%17%9%1
2331
16th to endDay
42%8%13%22%11%1
2510
June1st to 15thDay
43%7%12%23%11%1
2520
16th to endDay
42%7%13%21%14%
2520
July1st to 15thDay
42%7%10%22%15%1
2255
16th to endDay
38%9%13%23%14%1
2310
August1st to 15thDay
40%10%13%22%12%
2327
16th to endDay
41%8%14%19%12%3
2444
September1st to 15thDay
46%6%12%20%11%1
2061
16th to endDay
45%6%10%22%13%1
1980
October1st to 15thDay
51%6%11%18%12%
1825
16th to endDay
58%413%15%6%
1920
November1st to 15thDay
52%5%11%17%10%3
1726
16th to endDay
65%5%10%12%6%
1563
December1st to 15thDay
75%5%8%9%2
1560
16th to endDay
79%5%7%6%1
1580
January1st to 15thNight
73%47%9%4
2327
16th to endNight
73%5%10%8%2
2496
February1st to 15thNight
70%5%9%11%3
2287
16th to endNight
65%5%9%14%4
1940
March1st to 15thNight
59%6%10%15%7%
2001
16th to endNight
52%5%10%19%9%1
2112
April1st to 15thNight
54%5%10%16%12%
1863
16th to endNight
45%5%11%19%14%4
1620
May1st to 15thNight
49%6%12%18%10%2
1620
16th to endNight
39%6%13%23%13%3
1609
June1st to 15thNight
39%7%11%24%15%
1440
16th to endNight
37%8%12%22%16%2
1440
July1st to 15thNight
33%8%11%24%20%2
1473
16th to endNight
32%7%15%22%18%3
1595
August1st to 15thNight
32%7%14%27%16%1
1609
16th to endNight
33%6%12%26%17%3
1745
September1st to 15thNight
37%7%13%22%16%2
1896
16th to endNight
40%5%11%22%18%
1980
October1st to 15thNight
42%6%13%18%17%1
2134
16th to endNight
53%6%13%18%7%
2304
November1st to 15thNight
49%5%13%16%10%4
2459
16th to endNight
63%5%11%14%5%
2724
December1st to 15thNight
70%5%11%8%4
2730
16th to endNight
75%5%10%7%
2740

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
33%35%15%8%6%
90
16th to endDay
34%36%20%7%1
96
February1st to 15thDay
40%23%34%2
90
16th to endDay
19%32%43%4
81
March1st to 15thDay
30%15%32%16%5%
249
16th to endDay
28%19%26%17%6%1
288
April1st to 15thDay
27%19%27%17%9%
270
16th to endDay
23%16%29%15%10%3
270
May1st to 15thDay
23%18%28%20%7%2
288
16th to endDay
17%12%32%20%10%5%
331
June1st to 15thDay
16%11%31%26%13%1
315
16th to endDay
17%10%32%25%11%3
315
July1st to 15thDay
13%9%27%25%18%6%
305
16th to endDay
11%325%29%20%8%
326
August1st to 15thDay
8%7%25%25%21%11%
313
16th to endDay
13%8%20%24%18%14%
332
September1st to 15thDay
14%8%19%24%24%9%
315
16th to endDay
15%10%16%18%24%13%
314
October1st to 15thDay
21%10%25%20%19%2
315
16th to endDay
30%15%31%17%4
336
November1st to 15thDay
27%14%26%18%10%2
144
16th to endDay
21%30%32%12%2
91
December1st to 15thDay
28%22%30%13%32
90
16th to endDay
40%33%25%
74
January1st to 15thNight
31%25%30%10%2
720
16th to endNight
24%26%32%15%1
768
February1st to 15thNight
28%23%29%15%1
704
16th to endNight
26%21%33%16%2
631
March1st to 15thNight
26%20%29%19%3
720
16th to endNight
21%18%29%22%7%
768
April1st to 15thNight
26%15%32%20%4
704
16th to endNight
15%12%36%26%7%1
540
May1st to 15thNight
18%10%26%32%10%
540
16th to endNight
15%6%25%32%18%2
488
June1st to 15thNight
11%429%39%14%
360
16th to endNight
11%5%26%39%16%
360
July1st to 15thNight
7%324%38%23%3
453
16th to endNight
7%418%40%26%2
564
August1st to 15thNight
9%315%41%26%4
539
16th to endNight
12%316%30%34%2
599
September1st to 15thNight
15%5%17%31%26%3
720
16th to endNight
17%6%19%26%23%6%
717
October1st to 15thNight
19%9%25%26%17%1
720
16th to endNight
26%16%31%18%5%
768
November1st to 15thNight
20%15%28%25%8%1
760
16th to endNight
30%23%26%13%5%
780
December1st to 15thNight
32%23%26%13%4
780
16th to endNight
31%22%31%12%1
788
Page generated at 2017-12-21 07:04:49. Version ac04

Copyright 2017 A. Danko


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