Arunah Hill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Arunah Hill clear sky chart from 2005-11-05 to 2017-09-10.

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
28%
14853
16%
46767
7%
14821
38%
14821
18%
31042

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
18%
720
16%
2506
6%
716
31%
716
13%
1667
January16th to endNight
14%
768
16%
2676
4%
768
31%
768
12%
1776
February1st to 15thNight
11%
704
13%
2213
1%
701
26%
701
12%
1543
February16th to endNight
16%
631
19%
1893
6%
631
32%
631
14%
1274
March1st to 15thNight
17%
720
15%
2160
5%
720
29%
720
13%
1495
March16th to endNight
23%
768
22%
2004
7%
768
34%
768
19%
1356
April1st to 15thNight
19%
718
14%
1796
2%
718
26%
718
17%
1310
April16th to endNight
25%
642
16%
1722
4%
642
33%
642
21%
1188
May1st to 15thNight
24%
505
16%
1585
7%
505
33%
505
17%
1097
May16th to endNight
33%
375
12%
1497
9%
374
41%
374
16%
993
June1st to 15thNight
34%
360
11%
1440
8%
360
44%
360
15%
946
June16th to endNight
44%
360
11%
1440
11%
360
52%
360
21%
873
July1st to 15thNight
49%
340
12%
1360
15%
340
55%
340
22%
806
July16th to endNight
54%
376
15%
1418
17%
354
59%
354
24%
829
August1st to 15thNight
49%
473
16%
1544
10%
471
56%
471
28%
927
August16th to endNight
53%
764
19%
1910
10%
764
55%
764
32%
1263
September1st to 15thNight
43%
700
19%
1766
9%
700
47%
700
30%
1164
September16th to endNight
50%
657
24%
1815
16%
657
55%
657
33%
1112
October1st to 15thNight
33%
660
20%
1897
11%
660
43%
660
21%
1275
October16th to endNight
23%
704
13%
2249
4%
704
33%
704
17%
1512
November1st to 15thNight
29%
700
20%
2277
10%
700
42%
700
20%
1460
November16th to endNight
26%
720
16%
2391
8%
720
37%
720
15%
1603
December1st to 15thNight
20%
720
13%
2520
4%
720
31%
720
12%
1720
December16th to endNight
15%
768
15%
2688
4%
768
29%
768
10%
1853

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%7%35%5%35%5%5%7%34%
47875
Night
15%7%25%5%3445%7%38%
46937
Cloud CoverDay
16%6%25%5%35%5%5%7%35%
47885
Night
15%6%25%42445%7%39%
46942
TransparencyDay
45%7%13%19%12%1
47563
Night
42%7%14%20%12%1
46767
SeeingDay
21%16%27%19%10%3
5747
Night
20%17%28%23%8%
14853

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
12%8%35%7%36%6%6%7%31%
1432
16th to endDay
13%8%37%6%45%46%9%31%
1548
February1st to 15thDay
12%8%48%7%47%5%5%6%28%
1648
16th to endDay
15%8%38%6%36%45%6%32%
1580
March1st to 15thDay
16%11%35%5%345%5%7%30%
1790
16th to endDay
16%7%36%5%2445%5%37%
2217
April1st to 15thDay
17%8%36%5%34445%34%
2152
16th to endDay
15%6%36%5%245%5%6%37%
2238
May1st to 15thDay
24%7%36%5%345%45%29%
2376
16th to endDay
19%5%25%5%25%5%6%7%35%
2618
June1st to 15thDay
23%5%25%5%345%48%29%
2520
16th to endDay
17%5%35%6%36%5%6%9%29%
2520
July1st to 15thDay
13%5%35%6%36%6%6%8%33%
2520
16th to endDay
13%5%25%5%35%6%7%8%35%
2654
August1st to 15thDay
14%6%25%7%35%6%6%9%32%
2394
16th to endDay
13%5%25%445%5%6%7%38%
2292
September1st to 15thDay
15%5%246%45%5%48%38%
2082
16th to endDay
15%5%1442335%6%47%
1815
October1st to 15thDay
21%6%36%424435%35%
1733
16th to endDay
18%9%35%5%345%5%7%32%
1623
November1st to 15thDay
14%8%35%4235%5%6%40%
1581
16th to endDay
18%7%35%4145%46%38%
1566
December1st to 15thDay
17%8%36%6%36%347%31%
1440
16th to endDay
17%10%46%6%35%5%5%6%27%
1536
January1st to 15thNight
15%8%35%5%345%6%7%34%
2506
16th to endNight
12%8%36%6%35%5%6%7%33%
2676
February1st to 15thNight
13%8%46%447%5%7%6%31%
2212
16th to endNight
14%9%35%435%5%6%6%35%
1893
March1st to 15thNight
16%7%25%5%26%6%5%6%33%
2147
16th to endNight
14%6%35%4345%5%6%41%
2004
April1st to 15thNight
16%8%27%6%3445%5%34%
1796
16th to endNight
19%8%24423445%40%
1722
May1st to 15thNight
20%8%25%42445%7%33%
1585
16th to endNight
18%6%25%5%3445%7%35%
1495
June1st to 15thNight
22%6%25%423346%37%
1440
16th to endNight
17%323325%45%7%44%
1440
July1st to 15thNight
11%5%245%25%449%42%
1440
16th to endNight
11%43443347%8%44%
1514
August1st to 15thNight
10%424423448%47%
1554
16th to endNight
14%4144235%6%7%45%
1910
September1st to 15thNight
14%42442345%7%45%
1766
16th to endNight
14%414313437%50%
1815
October1st to 15thNight
20%6%25%42433442%
1897
16th to endNight
17%7%25%4345%47%36%
2249
November1st to 15thNight
14%7%35%424446%42%
2277
16th to endNight
15%7%35%6%35%446%36%
2391
December1st to 15thNight
18%6%35%5%346%5%7%31%
2520
16th to endNight
18%8%345%35%6%6%8%29%
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
13%8%346%36%6%6%8%32%
1432
16th to endDay
12%9%25%5%35%5%5%9%34%
1548
February1st to 15thDay
13%7%48%7%36%5%6%6%30%
1648
16th to endDay
15%8%37%6%36%45%6%33%
1580
March1st to 15thDay
17%9%45%6%3445%7%31%
1800
16th to endDay
16%6%46%43445%5%38%
2217
April1st to 15thDay
17%7%36%5%35%446%34%
2152
16th to endDay
14%6%35%435%46%6%38%
2238
May1st to 15thDay
24%7%35%6%34445%30%
2376
16th to endDay
18%5%25%5%35%5%5%7%34%
2618
June1st to 15thDay
23%6%24435%45%8%30%
2520
16th to endDay
16%6%25%6%36%5%7%8%30%
2520
July1st to 15thDay
11%6%36%6%46%6%6%8%33%
2520
16th to endDay
12%5%35%6%35%6%6%9%35%
2654
August1st to 15thDay
14%6%25%6%36%5%6%9%34%
2394
16th to endDay
12%5%25%5%35%5%6%8%39%
2292
September1st to 15thDay
14%5%25%6%35%45%6%40%
2082
16th to endDay
14%5%14324347%47%
1815
October1st to 15thDay
21%6%25%5%25%435%36%
1733
16th to endDay
17%8%26%6%34448%33%
1623
November1st to 15thDay
14%6%35%42446%6%40%
1581
16th to endDay
18%7%34424446%39%
1566
December1st to 15thDay
17%6%36%6%4445%7%33%
1440
16th to endDay
17%10%36%5%35%5%6%6%29%
1536
January1st to 15thNight
15%8%26%43446%8%35%
2506
16th to endNight
12%7%36%5%35%5%6%7%36%
2676
February1st to 15thNight
12%8%46%5%36%5%6%7%33%
2205
16th to endNight
14%8%34425%45%7%37%
1893
March1st to 15thNight
17%7%25%5%35%46%8%34%
2160
16th to endNight
14%6%25%42445%7%42%
2003
April1st to 15thNight
16%8%35%6%3445%6%35%
1796
16th to endNight
19%8%35%323445%41%
1722
May1st to 15thNight
20%7%35%42445%6%35%
1585
16th to endNight
17%5%25%5%245%6%7%35%
1495
June1st to 15thNight
22%5%25%5%23346%38%
1440
16th to endNight
16%42333445%8%43%
1440
July1st to 15thNight
12%4235%35%45%8%44%
1440
16th to endNight
11%4245%2446%8%44%
1514
August1st to 15thNight
10%5%1443345%8%47%
1554
16th to endNight
13%41343445%7%46%
1910
September1st to 15thNight
14%415%42345%7%46%
1766
16th to endNight
14%413312447%50%
1815
October1st to 15thNight
20%6%24423345%43%
1897
16th to endNight
18%7%2443445%7%37%
2249
November1st to 15thNight
14%7%24424336%44%
2277
16th to endNight
15%7%25%5%25%5%5%6%37%
2391
December1st to 15thNight
18%6%25%5%245%7%6%34%
2520
16th to endNight
17%7%345%35%5%6%8%31%
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
46%9%12%21%8%1
1433
16th to endDay
44%8%17%19%8%1
1548
February1st to 15thDay
51%8%15%15%9%
1651
16th to endDay
48%6%12%18%12%1
1580
March1st to 15thDay
50%7%12%18%9%1
1800
16th to endDay
45%6%11%17%15%4
2217
April1st to 15thDay
49%6%10%19%12%2
2152
16th to endDay
42%8%9%20%15%3
2238
May1st to 15thDay
54%5%8%18%11%2
2376
16th to endDay
45%8%14%17%12%1
2622
June1st to 15thDay
50%8%14%17%8%
2520
16th to endDay
45%9%15%16%11%
2520
July1st to 15thDay
45%8%12%20%11%
2371
16th to endDay
41%9%16%18%12%1
2487
August1st to 15thDay
43%9%14%21%9%1
2380
16th to endDay
38%8%13%25%13%1
2292
September1st to 15thDay
42%7%13%21%15%
2082
16th to endDay
35%7%10%24%21%1
1815
October1st to 15thDay
48%6%10%20%11%2
1733
16th to endDay
47%6%16%17%10%2
1623
November1st to 15thDay
41%7%17%20%11%1
1581
16th to endDay
44%5%14%21%12%1
1566
December1st to 15thDay
48%8%16%16%9%
1440
16th to endDay
50%10%16%14%8%
1536
January1st to 15thNight
44%8%15%18%11%1
2506
16th to endNight
44%8%15%18%11%1
2676
February1st to 15thNight
47%8%16%17%9%1
2213
16th to endNight
44%6%13%21%11%2
1893
March1st to 15thNight
46%8%13%20%9%1
2160
16th to endNight
40%7%11%19%16%5%
2004
April1st to 15thNight
47%6%12%17%14%1
1796
16th to endNight
44%5%10%19%16%3
1722
May1st to 15thNight
48%6%11%16%14%2
1585
16th to endNight
44%9%16%17%10%1
1497
June1st to 15thNight
47%6%14%21%9%
1440
16th to endNight
37%9%15%23%13%
1440
July1st to 15thNight
36%8%14%29%11%
1360
16th to endNight
35%8%17%25%12%1
1418
August1st to 15thNight
33%8%17%25%13%1
1544
16th to endNight
35%8%12%28%14%
1910
September1st to 15thNight
36%7%14%23%17%
1766
16th to endNight
32%6%10%25%23%1
1815
October1st to 15thNight
42%7%12%19%15%3
1897
16th to endNight
44%8%17%19%9%
2249
November1st to 15thNight
41%6%12%20%16%2
2277
16th to endNight
45%7%15%18%11%1
2391
December1st to 15thNight
45%9%16%19%8%
2520
16th to endNight
47%9%16%18%8%
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
25%31%26%10%6%
60
16th to endDay
28%28%28%13%
66
February1st to 15thDay
23%31%29%13%1
164
16th to endDay
20%28%30%17%2
239
March1st to 15thDay
31%21%28%14%2
270
16th to endDay
26%27%26%10%7%2
288
April1st to 15thDay
27%21%28%13%8%1
270
16th to endDay
21%17%30%18%7%4
270
May1st to 15thDay
32%19%22%14%6%4
288
16th to endDay
21%13%31%19%11%1
331
June1st to 15thDay
23%14%27%22%11%
315
16th to endDay
17%15%31%21%12%2
315
July1st to 15thDay
17%6%34%25%13%2
305
16th to endDay
13%8%32%26%15%3
326
August1st to 15thDay
15%9%26%24%16%7%
313
16th to endDay
13%6%22%27%17%11%
332
September1st to 15thDay
17%12%22%23%15%9%
294
16th to endDay
18%8%21%20%17%14%
254
October1st to 15thDay
23%11%20%24%14%4
255
16th to endDay
21%19%28%20%8%
247
November1st to 15thDay
22%17%24%22%10%2
235
16th to endDay
26%23%20%18%9%2
186
December1st to 15thDay
23%30%26%15%5%
60
16th to endDay
31%34%25%9%
64
January1st to 15thNight
21%23%32%18%3
720
16th to endNight
21%25%33%18%2
768
February1st to 15thNight
19%26%37%16%
704
16th to endNight
23%26%31%16%2
631
March1st to 15thNight
25%24%28%18%2
720
16th to endNight
20%24%28%20%5%
768
April1st to 15thNight
22%22%32%19%3
718
16th to endNight
24%18%29%18%8%
642
May1st to 15thNight
23%15%31%21%8%
505
16th to endNight
19%8%32%26%13%
375
June1st to 15thNight
23%9%26%30%10%
360
16th to endNight
16%5%27%38%11%
360
July1st to 15thNight
14%5%25%39%16%
340
16th to endNight
10%5%23%40%20%
376
August1st to 15thNight
13%427%36%16%1
473
16th to endNight
15%420%32%23%3
764
September1st to 15thNight
16%7%26%30%16%1
700
16th to endNight
17%6%21%29%20%4
657
October1st to 15thNight
25%12%23%27%10%1
660
16th to endNight
24%18%28%23%5%
704
November1st to 15thNight
21%17%28%23%8%1
700
16th to endNight
22%18%26%22%7%1
720
December1st to 15thNight
23%22%30%17%5%
720
16th to endNight
25%27%29%15%2
768
Page generated at 2017-09-11 19:35:33. Version ac04

Copyright 2017 A. Danko


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