This page made possible by the sponsorship of: Indiana Astronomical Society.

Indianapolis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Indianapolis clear sky chart from 2005-11-05 to 2018-03-11.

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%
16548
18%
49027
11%
16503
44%
16503
23%
32972

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%
975
14%
2716
5%
970
26%
970
15%
2069
January16th to endNight
19%
985
12%
2854
6%
985
26%
985
15%
2173
February1st to 15thNight
21%
763
11%
2292
4%
761
27%
761
15%
1682
February16th to endNight
22%
683
14%
2049
6%
683
29%
683
15%
1522
March1st to 15thNight
24%
764
14%
2277
7%
764
29%
764
19%
1612
March16th to endNight
28%
716
15%
2060
6%
716
36%
716
19%
1475
April1st to 15thNight
31%
539
18%
1797
10%
539
42%
539
21%
1176
April16th to endNight
32%
540
21%
1698
10%
540
43%
540
24%
1098
May1st to 15thNight
31%
540
14%
1620
7%
540
38%
540
19%
1155
May16th to endNight
50%
563
17%
1648
12%
561
54%
561
28%
1081
June1st to 15thNight
57%
540
17%
1440
13%
540
60%
540
37%
890
June16th to endNight
57%
540
19%
1440
13%
540
63%
540
34%
909
July1st to 15thNight
60%
510
16%
1360
11%
510
64%
510
36%
850
July16th to endNight
70%
564
25%
1464
19%
531
74%
531
45%
821
August1st to 15thNight
67%
539
22%
1612
19%
536
70%
536
37%
929
August16th to endNight
70%
573
23%
1910
22%
573
74%
573
36%
1029
September1st to 15thNight
61%
607
26%
1867
22%
607
66%
607
33%
1097
September16th to endNight
59%
717
27%
1980
21%
717
63%
717
35%
1201
October1st to 15thNight
51%
720
27%
1980
20%
720
58%
720
35%
1217
October16th to endNight
30%
768
21%
2468
15%
768
39%
768
23%
1544
November1st to 15thNight
38%
760
24%
2471
17%
760
49%
760
27%
1486
November16th to endNight
29%
780
20%
2535
13%
780
39%
780
19%
1706
December1st to 15thNight
21%
822
12%
2577
6%
822
28%
822
14%
1923
December16th to endNight
17%
1040
12%
2912
4%
1040
25%
1040
12%
2327

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
15%7%36%5%3445%7%36%
49595
Night
15%7%35%42445%6%39%
49201
Cloud CoverDay
15%7%35%5%3445%7%36%
49604
Night
15%7%35%5%24446%39%
49206
TransparencyDay
46%5%11%20%12%2
49287
Night
45%5%11%21%14%2
49027
SeeingDay
16%10%26%23%16%7%
6373
Night
18%9%28%27%14%1
16549

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
21%14%49%433346%24%
1552
16th to endDay
14%15%6%7%6%44345%27%
1717
February1st to 15thDay
15%13%5%8%5%35%345%27%
1900
16th to endDay
17%14%5%7%6%34246%27%
1710
March1st to 15thDay
20%8%48%5%25%436%29%
1910
16th to endDay
17%11%46%435%35%7%30%
2175
April1st to 15thDay
20%7%2442435%6%36%
2151
16th to endDay
18%6%35%5%34346%36%
2262
May1st to 15thDay
21%8%46%5%34446%31%
2331
16th to endDay
12%5%36%6%45%5%7%7%37%
2464
June1st to 15thDay
10%5%245%35%5%6%8%41%
2520
16th to endDay
9%5%25%5%45%5%5%9%41%
2520
July1st to 15thDay
11%5%25%5%345%7%9%39%
2520
16th to endDay
6%3245%36%7%7%11%41%
2601
August1st to 15thDay
9%315%436%6%7%9%41%
2334
16th to endDay
8%4245%36%5%6%9%41%
2292
September1st to 15thDay
12%5%24435%45%7%42%
2079
16th to endDay
11%5%1442345%7%49%
1980
October1st to 15thDay
15%5%244236%5%6%41%
1980
16th to endDay
17%6%36%5%23447%38%
1752
November1st to 15thDay
14%5%35%433445%46%
1717
16th to endDay
19%9%46%424446%34%
1755
December1st to 15thDay
21%12%49%434445%26%
1709
16th to endDay
23%14%5%7%5%23345%23%
1664
January1st to 15thNight
20%10%5%7%5%34435%28%
2716
16th to endNight
16%13%6%8%6%3334428%
2854
February1st to 15thNight
18%11%5%7%6%23335%30%
2290
16th to endNight
17%12%5%7%5%34445%30%
2049
March1st to 15thNight
17%9%37%434446%34%
2264
16th to endNight
17%8%36%5%3445%6%34%
2060
April1st to 15thNight
15%7%34425%446%40%
1797
16th to endNight
17%5%344245%5%7%40%
1698
May1st to 15thNight
19%8%35%43445%7%33%
1620
16th to endNight
12%325%5%35%5%6%9%39%
1646
June1st to 15thNight
7%5%3442445%8%49%
1440
16th to endNight
7%315%336%6%6%10%45%
1440
July1st to 15thNight
8%3145%2446%10%47%
1440
16th to endNight
6%32332445%8%55%
1564
August1st to 15thNight
5%313435%5%7%8%50%
1623
16th to endNight
5%3235%345%5%9%53%
1910
September1st to 15thNight
10%42442345%7%50%
1867
16th to endNight
10%5%2342345%6%51%
1980
October1st to 15thNight
11%4244245%5%7%48%
1980
16th to endNight
18%6%24423346%43%
2468
November1st to 15thNight
13%6%25%32345%5%46%
2471
16th to endNight
19%9%34423346%37%
2535
December1st to 15thNight
21%12%5%8%5%2333428%
2577
16th to endNight
24%13%5%8%5%3333424%
2912

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
21%13%49%423346%23%
1552
16th to endDay
15%14%6%8%6%35%336%26%
1717
February1st to 15thDay
16%13%5%8%6%44445%27%
1900
16th to endDay
18%13%5%7%6%3335%5%27%
1710
March1st to 15thDay
21%8%47%5%24446%28%
1920
16th to endDay
17%10%45%5%34446%31%
2174
April1st to 15thDay
20%8%3343435%6%36%
2151
16th to endDay
19%6%36%5%34346%36%
2262
May1st to 15thDay
21%7%46%6%35%445%31%
2331
16th to endDay
12%5%36%6%45%47%7%37%
2464
June1st to 15thDay
11%4245%345%6%8%42%
2520
16th to endDay
9%5%245%35%46%9%42%
2520
July1st to 15thDay
11%5%25%6%345%6%10%39%
2520
16th to endDay
7%2245%36%7%7%11%41%
2601
August1st to 15thDay
9%425%435%6%6%9%42%
2334
16th to endDay
8%425%5%36%5%6%9%42%
2292
September1st to 15thDay
12%5%245%3445%7%43%
2079
16th to endDay
11%5%23434446%49%
1980
October1st to 15thDay
16%5%245%245%5%7%41%
1980
16th to endDay
17%6%26%5%24447%38%
1752
November1st to 15thDay
14%5%25%42435%5%46%
1717
16th to endDay
18%9%5%6%424346%34%
1755
December1st to 15thDay
22%12%48%5%34345%25%
1709
16th to endDay
23%15%5%7%5%23245%23%
1664
January1st to 15thNight
20%10%47%6%34445%28%
2716
16th to endNight
16%13%6%8%6%3443428%
2854
February1st to 15thNight
18%11%5%7%5%24345%30%
2283
16th to endNight
17%12%47%6%24445%30%
2049
March1st to 15thNight
18%9%36%5%34446%34%
2277
16th to endNight
17%8%36%5%3445%6%34%
2060
April1st to 15thNight
16%7%3442445%6%40%
1797
16th to endNight
17%5%3442445%7%41%
1698
May1st to 15thNight
19%7%35%42445%7%33%
1619
16th to endNight
12%425%435%5%7%8%40%
1646
June1st to 15thNight
8%5%2442445%7%49%
1440
16th to endNight
8%314435%6%7%9%45%
1440
July1st to 15thNight
8%3235%3446%8%48%
1440
16th to endNight
6%32322345%9%56%
1564
August1st to 15thNight
6%3135%345%7%7%51%
1623
16th to endNight
5%31443446%9%52%
1910
September1st to 15thNight
10%42442335%7%50%
1867
16th to endNight
10%5%23433447%50%
1980
October1st to 15thNight
11%32442445%7%49%
1980
16th to endNight
18%6%14423346%42%
2468
November1st to 15thNight
13%6%25%32345%5%45%
2471
16th to endNight
19%8%34423345%37%
2535
December1st to 15thNight
21%12%5%8%5%22335%29%
2577
16th to endNight
24%13%5%8%5%3333424%
2912

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
61%48%15%9%
1553
16th to endDay
59%412%18%4
1717
February1st to 15thDay
58%410%15%8%
1902
16th to endDay
58%310%19%6%
1710
March1st to 15thDay
56%412%17%7%
1920
16th to endDay
53%5%14%20%5%
2175
April1st to 15thDay
47%5%11%22%11%1
2151
16th to endDay
48%411%18%11%4
2262
May1st to 15thDay
53%6%11%18%9%
2331
16th to endDay
43%8%11%19%15%2
2468
June1st to 15thDay
37%7%13%23%16%2
2520
16th to endDay
36%7%13%21%16%3
2520
July1st to 15thDay
40%7%11%20%17%2
2371
16th to endDay
31%10%18%24%13%1
2438
August1st to 15thDay
34%8%12%24%17%1
2321
16th to endDay
34%8%12%23%15%6%
2292
September1st to 15thDay
39%5%10%21%18%4
2079
16th to endDay
35%5%8%25%23%1
1980
October1st to 15thDay
40%5%9%23%17%2
1980
16th to endDay
45%5%11%23%13%
1752
November1st to 15thDay
40%310%23%17%4
1717
16th to endDay
51%39%22%11%1
1755
December1st to 15thDay
60%410%16%7%
1709
16th to endDay
63%310%16%3
1664
January1st to 15thNight
58%47%18%10%
2716
16th to endNight
59%411%18%6%
2854
February1st to 15thNight
56%413%16%8%1
2292
16th to endNight
56%411%18%8%
2049
March1st to 15thNight
50%411%20%10%2
2277
16th to endNight
50%5%11%23%7%1
2060
April1st to 15thNight
44%5%9%22%16%2
1797
16th to endNight
42%5%9%21%13%7%
1698
May1st to 15thNight
49%7%11%19%10%1
1620
16th to endNight
38%8%12%20%14%4
1648
June1st to 15thNight
32%6%12%25%21%2
1440
16th to endNight
31%9%13%22%19%3
1440
July1st to 15thNight
33%6%15%21%18%5%
1360
16th to endNight
24%6%14%33%18%3
1464
August1st to 15thNight
28%7%15%23%22%2
1612
16th to endNight
27%6%13%25%20%6%
1910
September1st to 15thNight
32%5%10%22%22%6%
1867
16th to endNight
32%5%8%22%26%3
1980
October1st to 15thNight
33%5%10%23%23%3
1980
16th to endNight
42%311%25%14%1
2468
November1st to 15thNight
38%39%22%20%4
2471
16th to endNight
48%310%23%13%
2535
December1st to 15thNight
58%39%17%10%
2577
16th to endNight
63%48%15%6%
2912

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%14%30%18%2
135
16th to endDay
22%25%38%13%
144
February1st to 15thDay
25%30%29%11%2
135
16th to endDay
30%16%35%15%2
120
March1st to 15thDay
27%22%36%12%1
136
16th to endDay
21%17%32%17%8%1
288
April1st to 15thDay
18%18%29%22%10%
270
16th to endDay
24%9%28%20%12%4
270
May1st to 15thDay
23%13%29%20%9%3
288
16th to endDay
16%7%31%18%16%10%
364
June1st to 15thDay
12%426%33%17%5%
495
16th to endDay
11%10%28%29%14%6%
495
July1st to 15thDay
14%326%27%18%9%
475
16th to endDay
6%315%32%26%16%
461
August1st to 15thDay
12%212%23%31%17%
313
16th to endDay
9%415%25%31%13%
332
September1st to 15thDay
13%414%26%26%14%
315
16th to endDay
12%7%16%17%31%14%
314
October1st to 15thDay
15%8%24%26%20%5%
315
16th to endDay
16%13%42%22%4
159
November1st to 15thDay
20%14%23%20%18%2
135
16th to endDay
24%14%40%15%5%
135
December1st to 15thDay
17%25%35%14%5%1
135
16th to endDay
31%26%34%6%
144
January1st to 15thNight
24%14%36%19%4
975
16th to endNight
22%16%33%24%2
985
February1st to 15thNight
23%15%33%24%2
764
16th to endNight
24%12%35%23%3
683
March1st to 15thNight
21%13%36%23%5%
764
16th to endNight
20%11%33%26%6%1
716
April1st to 15thNight
17%13%34%26%7%
539
16th to endNight
18%8%35%25%10%1
540
May1st to 15thNight
19%7%32%28%10%
540
16th to endNight
12%326%33%22%1
563
June1st to 15thNight
9%323%45%17%1
540
16th to endNight
9%124%39%22%1
540
July1st to 15thNight
8%122%34%30%2
510
16th to endNight
8%15%35%35%5%
564
August1st to 15thNight
7%115%37%32%5%
539
16th to endNight
6%112%34%39%5%
573
September1st to 15thNight
12%317%32%28%5%
607
16th to endNight
12%416%27%33%5%
717
October1st to 15thNight
12%6%24%29%21%4
720
16th to endNight
20%11%34%23%8%
768
November1st to 15thNight
15%11%31%25%14%1
760
16th to endNight
22%14%29%24%8%
780
December1st to 15thNight
26%12%32%20%7%
822
16th to endNight
30%12%33%20%4
1040
Page generated at 2018-03-12 13:28:02. Version ac04

Copyright 2018 A. Danko


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