Evansville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Evansville clear sky chart from 2005-11-05 to

2017-09-12
.

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
39%
15710
22%
46769
14%
15666
47%
15666
24%
29547

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
23%
900
19%
2506
8%
895
32%
895
19%
1736
January16th to endNight
22%
933
18%
2559
6%
933
31%
933
19%
1798
February1st to 15thNight
19%
704
18%
2112
6%
701
28%
701
16%
1464
February16th to endNight
21%
631
18%
1893
7%
631
31%
631
18%
1271
March1st to 15thNight
24%
720
17%
2160
8%
720
32%
720
18%
1460
March16th to endNight
33%
651
16%
2022
9%
651
41%
651
18%
1377
April1st to 15thNight
35%
539
22%
1797
14%
539
48%
539
24%
1073
April16th to endNight
35%
540
21%
1776
13%
540
46%
540
22%
1100
May1st to 15thNight
38%
539
18%
1619
9%
539
46%
539
22%
1069
May16th to endNight
47%
561
19%
1637
10%
561
55%
561
24%
1036
June1st to 15thNight
53%
540
22%
1440
13%
540
60%
540
32%
855
June16th to endNight
60%
540
24%
1440
16%
540
65%
540
38%
829
July1st to 15thNight
60%
510
20%
1360
15%
510
63%
510
35%
835
July16th to endNight
64%
564
24%
1449
18%
531
73%
531
39%
831
August1st to 15thNight
69%
539
24%
1732
24%
536
72%
536
36%
925
August16th to endNight
70%
573
27%
1910
30%
573
74%
573
35%
1023
September1st to 15thNight
63%
560
27%
1797
27%
560
67%
560
34%
1019
September16th to endNight
55%
657
27%
1815
18%
657
61%
657
32%
1096
October1st to 15thNight
51%
660
31%
1840
23%
660
57%
660
34%
1084
October16th to endNight
39%
704
26%
2216
18%
704
49%
704
27%
1343
November1st to 15thNight
39%
700
29%
2276
22%
700
51%
700
30%
1282
November16th to endNight
29%
720
24%
2340
13%
720
44%
720
21%
1427
December1st to 15thNight
27%
765
15%
2385
9%
765
34%
765
16%
1664
December16th to endNight
18%
960
16%
2688
5%
960
28%
960
16%
1950

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
13%5%25%43445%7%41%
47896
Night
13%6%25%42345%7%44%
46948
TransparencyDay
40%5%12%23%15%2
47578
Night
39%411%23%16%3
46771
SeeingDay
14%12%20%22%20%10%
5742
Night
14%19%21%26%15%2
15713

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
21%7%47%5%23445%32%
1432
16th to endDay
13%9%46%5%33447%37%
1659
February1st to 15thDay
16%10%46%423347%36%
1750
16th to endDay
13%8%48%6%46%5%6%5%32%
1580
March1st to 15thDay
20%8%35%424335%38%
1800
16th to endDay
17%9%36%5%345%5%7%33%
2210
April1st to 15thDay
13%5%35%43445%8%41%
2151
16th to endDay
15%5%35%5%33447%40%
2184
May1st to 15thDay
18%6%25%5%2446%8%34%
2331
16th to endDay
9%5%26%5%46%5%6%8%37%
2474
June1st to 15thDay
7%314435%46%8%47%
2520
16th to endDay
6%2245%35%5%7%10%45%
2520
July1st to 15thDay
11%425%435%5%7%10%39%
2520
16th to endDay
5%2145%46%6%7%11%42%
2619
August1st to 15thDay
6%4245%36%5%6%10%44%
2214
16th to endDay
7%324435%47%9%46%
2292
September1st to 15thDay
10%425%6%345%6%8%44%
2071
16th to endDay
12%425%433346%49%
1815
October1st to 15thDay
11%414323347%52%
1788
16th to endDay
14%5%24323345%50%
1656
November1st to 15thDay
11%5%24423447%50%
1582
16th to endDay
20%7%23323335%43%
1620
December1st to 15thDay
23%8%36%32424435%
1572
16th to endDay
19%11%26%413245%37%
1536
January1st to 15thNight
18%7%36%433345%37%
2506
16th to endNight
16%9%36%5%2445%6%36%
2559
February1st to 15thNight
17%9%46%5%23446%35%
2103
16th to endNight
15%8%45%43445%6%37%
1893
March1st to 15thNight
17%8%35%5%34445%39%
2160
16th to endNight
18%5%35%425%5%5%6%36%
2022
April1st to 15thNight
14%6%23323446%47%
1797
16th to endNight
17%5%35%422347%42%
1776
May1st to 15thNight
14%6%26%5%2345%7%39%
1619
16th to endNight
6%326%5%46%5%6%9%42%
1636
June1st to 15thNight
7%424435%46%9%49%
1440
16th to endNight
5%2144245%8%9%52%
1440
July1st to 15thNight
7%42441445%9%49%
1440
16th to endNight
5%213425%46%10%51%
1547
August1st to 15thNight
5%31432346%8%54%
1743
16th to endNight
441342446%10%52%
1910
September1st to 15thNight
10%3144245%5%8%51%
1797
16th to endNight
10%5%24423347%49%
1815
October1st to 15thNight
10%425%423325%55%
1840
16th to endNight
16%5%2432333449%
2216
November1st to 15thNight
12%424422346%51%
2276
16th to endNight
18%6%23423345%46%
2340
December1st to 15thNight
22%8%35%423445%34%
2385
16th to endNight
21%9%35%424345%33%
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
52%411%20%11%
1433
16th to endDay
46%312%28%8%
1659
February1st to 15thDay
48%311%24%10%1
1752
16th to endDay
51%5%12%20%10%
1580
March1st to 15thDay
50%39%22%12%1
1800
16th to endDay
50%5%13%23%6%1
2211
April1st to 15thDay
40%5%12%24%17%
2151
16th to endDay
43%412%25%12%2
2184
May1st to 15thDay
47%6%13%21%10%
2331
16th to endDay
41%7%14%19%13%2
2478
June1st to 15thDay
32%6%12%27%19%2
2520
16th to endDay
32%8%13%21%19%4
2520
July1st to 15thDay
38%6%13%21%14%4
2371
16th to endDay
29%8%18%25%14%2
2455
August1st to 15thDay
33%6%14%24%18%2
2201
16th to endDay
32%6%14%22%19%5%
2292
September1st to 15thDay
36%6%9%22%19%4
2071
16th to endDay
36%46%22%25%4
1815
October1st to 15thDay
31%49%26%22%4
1788
16th to endDay
36%28%28%19%3
1656
November1st to 15thDay
34%410%23%19%7%
1582
16th to endDay
44%37%25%15%2
1620
December1st to 15thDay
53%212%20%10%1
1572
16th to endDay
50%313%22%8%
1536
January1st to 15thNight
49%39%22%14%1
2506
16th to endNight
48%412%22%10%1
2559
February1st to 15thNight
50%310%24%9%1
2112
16th to endNight
46%413%23%11%
1893
March1st to 15thNight
47%410%21%12%3
2160
16th to endNight
46%6%14%20%10%1
2022
April1st to 15thNight
37%411%24%18%4
1797
16th to endNight
40%49%25%16%4
1776
May1st to 15thNight
43%5%12%23%14%
1620
16th to endNight
35%8%13%20%17%4
1638
June1st to 15thNight
30%5%13%26%21%3
1440
16th to endNight
24%7%15%22%23%5%
1440
July1st to 15thNight
31%6%12%27%17%5%
1360
16th to endNight
26%5%15%30%18%3
1449
August1st to 15thNight
26%5%16%24%23%4
1732
16th to endNight
26%6%12%27%21%5%
1910
September1st to 15thNight
30%5%8%26%21%7%
1797
16th to endNight
34%38%21%24%7%
1815
October1st to 15thNight
32%37%22%26%6%
1840
16th to endNight
39%26%28%17%5%
2216
November1st to 15thNight
33%39%21%24%8%
2276
16th to endNight
40%39%25%18%2
2340
December1st to 15thNight
51%411%20%11%1
2385
16th to endNight
53%311%19%10%1
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
37%7%34%12%7%
90
16th to endDay
14%26%39%17%2
96
February1st to 15thDay
22%14%45%14%3
90
16th to endDay
20%18%33%22%4
81
March1st to 15thDay
27%11%44%14%2
90
16th to endDay
18%20%28%22%8%
261
April1st to 15thDay
15%18%29%22%13%
270
16th to endDay
18%15%24%21%15%4
270
May1st to 15thDay
20%18%24%20%10%5%
288
16th to endDay
15%13%23%21%15%9%
374
June1st to 15thDay
9%15%14%22%25%12%
495
16th to endDay
7%14%22%28%17%8%
495
July1st to 15thDay
13%9%14%25%23%13%
475
16th to endDay
5%12%6%22%31%20%
479
August1st to 15thDay
13%7%7%19%29%23%
313
16th to endDay
10%5%8%21%38%15%
332
September1st to 15thDay
9%7%12%20%29%20%
299
16th to endDay
14%9%11%20%27%16%
254
October1st to 15thDay
10%7%20%24%26%9%
228
16th to endDay
16%232%29%18%1
96
November1st to 15thDay
7%7%23%30%20%11%
90
16th to endDay
33%6%27%22%8%1
90
December1st to 15thDay
17%14%33%25%44
90
16th to endDay
30%15%41%8%4
96
January1st to 15thNight
17%26%29%21%5%
900
16th to endNight
18%25%29%23%2
933
February1st to 15thNight
20%27%28%21%2
704
16th to endNight
17%25%31%23%2
631
March1st to 15thNight
19%24%27%25%3
720
16th to endNight
17%22%22%28%8%
651
April1st to 15thNight
14%22%25%27%8%1
539
16th to endNight
17%20%22%26%12%
540
May1st to 15thNight
14%20%21%31%10%1
540
16th to endNight
7%18%17%29%22%3
563
June1st to 15thNight
9%17%13%31%25%2
540
16th to endNight
417%11%37%25%2
540
July1st to 15thNight
9%11%10%29%35%3
510
16th to endNight
5%16%6%26%36%9%
564
August1st to 15thNight
7%9%5%29%39%8%
539
16th to endNight
6%8%6%31%39%6%
573
September1st to 15thNight
10%9%10%26%36%6%
560
16th to endNight
12%11%11%26%31%6%
657
October1st to 15thNight
12%12%18%26%24%5%
660
16th to endNight
16%13%26%28%12%1
704
November1st to 15thNight
10%19%25%27%15%1
700
16th to endNight
20%23%24%21%9%
720
December1st to 15thNight
23%21%22%23%6%1
765
16th to endNight
22%25%29%18%3
960
Page generated at 2017-09-13 06:39:05. Version ac04

Copyright 2017 A. Danko


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