Olivet
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Olivet clear sky chart from 2005-11-05 to 2017-10-16.

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
42%
16165
20%
47129
12%
16119
49%
16119
31%
28771

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
33%
900
15%
2506
8%
895
39%
895
24%
1677
January16th to endNight
30%
960
18%
2559
8%
960
38%
960
25%
1747
February1st to 15thNight
30%
879
12%
2288
4%
875
34%
875
23%
1637
February16th to endNight
38%
652
21%
1914
9%
652
47%
652
28%
1192
March1st to 15thNight
37%
615
19%
2055
12%
615
47%
615
26%
1251
March16th to endNight
30%
576
16%
2112
12%
576
39%
576
21%
1321
April1st to 15thNight
33%
539
19%
1810
13%
539
44%
539
26%
1100
April16th to endNight
32%
540
18%
1620
13%
540
42%
540
24%
1061
May1st to 15thNight
40%
540
19%
1620
11%
540
48%
540
32%
975
May16th to endNight
43%
562
16%
1630
6%
561
48%
561
30%
1027
June1st to 15thNight
49%
540
17%
1272
5%
540
52%
540
41%
811
June16th to endNight
64%
540
23%
1260
9%
540
66%
540
57%
712
July1st to 15thNight
66%
510
17%
1318
7%
510
69%
510
47%
746
July16th to endNight
73%
564
24%
1518
17%
531
74%
531
53%
771
August1st to 15thNight
68%
539
22%
1610
21%
536
71%
536
43%
862
August16th to endNight
59%
573
27%
1719
24%
573
69%
573
43%
917
September1st to 15thNight
57%
540
24%
1920
22%
540
67%
540
37%
976
September16th to endNight
51%
537
30%
1980
24%
537
63%
537
38%
963
October1st to 15thNight
39%
645
29%
2085
19%
645
49%
645
31%
1181
October16th to endNight
42%
779
24%
2195
14%
779
48%
779
35%
1314
November1st to 15thNight
42%
875
27%
2275
12%
875
50%
875
39%
1338
November16th to endNight
39%
900
22%
2487
12%
900
46%
900
34%
1515
December1st to 15thNight
31%
900
15%
2520
6%
900
38%
900
24%
1715
December16th to endNight
34%
960
17%
2856
9%
960
42%
960
21%
1962

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
11%6%25%42445%7%45%
48278
Night
9%6%2442445%7%48%
47307
Cloud CoverDay
11%6%25%42445%7%45%
48289
Night
9%6%25%42445%7%48%
47311
Cloud CoverDay
11%6%25%42445%7%44%
48287
Night
9%6%25%42445%6%47%
47311
TransparencyDay
38%5%15%26%12%1
47974
Night
36%414%26%15%2
47129
SeeingDay
13%6%28%32%16%2
6156
Night
12%7%31%35%11%
16167

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
6%7%46%8%36%5%6%5%38%
1432
16th to endDay
8%11%410%6%26%45%6%32%
1664
February1st to 15thDay
13%9%47%5%4445%6%34%
1575
16th to endDay
9%7%47%6%35%5%6%7%36%
1569
March1st to 15thDay
12%7%37%5%3435%6%40%
1893
16th to endDay
17%10%36%6%2445%6%34%
2112
April1st to 15thDay
16%5%25%5%24347%41%
2135
16th to endDay
23%7%25%5%23445%35%
2340
May1st to 15thDay
16%4245%34447%42%
2331
16th to endDay
15%6%26%3345%46%39%
2484
June1st to 15thDay
14%425%4245%6%8%43%
2685
16th to endDay
7%2133245%6%8%54%
2700
July1st to 15thDay
6%31342446%9%54%
2560
16th to endDay
5%21332446%7%58%
2544
August1st to 15thDay
8%4245%345%6%8%46%
2340
16th to endDay
8%325%323346%56%
2483
September1st to 15thDay
12%413323446%52%
2038
16th to endDay
9%313313346%59%
1980
October1st to 15thDay
14%5%1331343453%
1863
16th to endDay
14%6%24212245%51%
1695
November1st to 15thDay
6%7%3332446%6%50%
1583
16th to endDay
9%8%25%43445%8%43%
1470
December1st to 15thDay
12%10%47%5%24446%37%
1437
16th to endDay
13%9%5%8%7%24246%33%
1365
January1st to 15thNight
6%7%47%7%45%5%5%7%37%
2506
16th to endNight
8%9%46%6%3445%7%38%
2559
February1st to 15thNight
11%11%46%6%25%445%37%
2285
16th to endNight
7%6%35%6%245%45%47%
1914
March1st to 15thNight
11%7%145%25%45%7%44%
2043
16th to endNight
12%8%36%424346%42%
2112
April1st to 15thNight
13%6%3442435%7%44%
1810
16th to endNight
16%5%35%5%2445%5%41%
1620
May1st to 15thNight
14%41342335%6%50%
1620
16th to endNight
13%5%145%3335%7%45%
1628
June1st to 15thNight
9%42442445%9%50%
1272
16th to endNight
431223448%64%
1260
July1st to 15thNight
5%21342446%7%57%
1398
16th to endNight
211332346%8%61%
1623
August1st to 15thNight
42233245%5%10%55%
1620
16th to endNight
6%32232345%7%58%
1719
September1st to 15thNight
9%224323346%58%
1920
16th to endNight
8%212323246%61%
1980
October1st to 15thNight
16%313223345%53%
2085
16th to endNight
13%5%23323336%52%
2195
November1st to 15thNight
8%415%324346%54%
2275
16th to endNight
8%5%245%3436%7%47%
2487
December1st to 15thNight
10%10%37%5%25%45%6%38%
2520
16th to endNight
11%10%47%5%34346%37%
2856

Percentage Cloud Cover SW (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
6%8%47%7%46%5%5%6%37%
1432
16th to endDay
8%11%410%6%27%446%31%
1664
February1st to 15thDay
12%9%47%5%445%5%6%33%
1575
16th to endDay
9%7%38%6%35%5%6%6%36%
1569
March1st to 15thDay
12%7%36%5%3445%6%40%
1904
16th to endDay
16%9%46%5%24446%34%
2112
April1st to 15thDay
16%5%25%5%24447%41%
2135
16th to endDay
23%6%25%42445%5%34%
2340
May1st to 15thDay
16%5%245%3335%7%41%
2331
16th to endDay
15%6%26%4345%47%39%
2484
June1st to 15thDay
14%42442446%8%42%
2685
16th to endDay
7%31332446%8%53%
2700
July1st to 15thDay
6%21342346%9%53%
2560
16th to endDay
5%21322446%7%58%
2544
August1st to 15thDay
8%425%5%345%6%8%45%
2340
16th to endDay
7%324323346%56%
2483
September1st to 15thDay
12%413323446%52%
2038
16th to endDay
9%313313346%58%
1980
October1st to 15thDay
14%5%1332333353%
1863
16th to endDay
15%6%24213236%51%
1695
November1st to 15thDay
6%7%2342446%6%50%
1583
16th to endDay
10%8%26%42445%8%43%
1470
December1st to 15thDay
12%10%47%6%1445%6%37%
1437
16th to endDay
12%10%5%7%7%34337%33%
1365
January1st to 15thNight
6%7%47%7%46%5%5%7%37%
2506
16th to endNight
8%10%37%6%3445%6%38%
2559
February1st to 15thNight
11%11%47%6%24445%37%
2278
16th to endNight
7%6%36%5%2445%6%46%
1914
March1st to 15thNight
11%7%24435%45%7%44%
2055
16th to endNight
12%8%45%434446%41%
2112
April1st to 15thNight
13%6%3442435%7%44%
1810
16th to endNight
16%6%35%43345%5%40%
1620
May1st to 15thNight
15%413323346%50%
1619
16th to endNight
13%5%24424347%45%
1628
June1st to 15thNight
9%424424449%50%
1272
16th to endNight
42122335%8%64%
1260
July1st to 15thNight
5%21332446%7%57%
1398
16th to endNight
211232346%8%62%
1623
August1st to 15thNight
42233235%5%10%55%
1620
16th to endNight
6%323413446%59%
1719
September1st to 15thNight
8%21431335%5%58%
1920
16th to endNight
7%312323346%61%
1980
October1st to 15thNight
16%313213345%53%
2085
16th to endNight
13%5%24323336%52%
2195
November1st to 15thNight
8%5%15%424346%54%
2275
16th to endNight
8%5%2443446%7%47%
2487
December1st to 15thNight
10%9%37%5%25%45%6%37%
2520
16th to endNight
12%10%46%5%34346%37%
2856

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
6%8%47%7%46%5%6%6%36%
1432
16th to endDay
7%12%411%6%36%445%31%
1664
February1st to 15thDay
12%9%47%5%45%45%5%33%
1575
16th to endDay
8%7%48%6%445%6%8%35%
1569
March1st to 15thDay
12%7%38%434446%40%
1904
16th to endDay
16%10%46%434446%34%
2110
April1st to 15thDay
16%6%245%34446%41%
2135
16th to endDay
22%7%25%43345%5%34%
2340
May1st to 15thDay
16%5%2442445%7%42%
2331
16th to endDay
15%6%36%5%24447%38%
2484
June1st to 15thDay
14%4244245%5%8%42%
2685
16th to endDay
7%31342447%8%53%
2700
July1st to 15thDay
6%21342345%9%54%
2560
16th to endDay
421332446%8%58%
2544
August1st to 15thDay
7%5%245%35%47%8%45%
2340
16th to endDay
7%324423346%56%
2483
September1st to 15thDay
12%423313447%51%
2038
16th to endDay
9%413313246%58%
1980
October1st to 15thDay
14%5%2331333453%
1863
16th to endDay
14%6%34212246%50%
1695
November1st to 15thDay
6%7%3342445%6%50%
1583
16th to endDay
10%7%26%42445%8%43%
1470
December1st to 15thDay
12%10%48%5%2345%5%37%
1437
16th to endDay
13%10%5%8%7%34346%32%
1365
January1st to 15thNight
6%7%47%7%46%5%5%7%36%
2506
16th to endNight
8%9%47%6%245%5%7%38%
2559
February1st to 15thNight
11%11%5%6%6%23445%37%
2278
16th to endNight
7%6%36%5%3446%6%46%
1914
March1st to 15thNight
11%7%3443445%6%44%
2055
16th to endNight
12%8%36%424445%42%
2112
April1st to 15thNight
12%6%35%42335%8%43%
1810
16th to endNight
16%7%35%42345%6%40%
1620
May1st to 15thNight
13%5%13323347%49%
1619
16th to endNight
13%5%15%424447%45%
1628
June1st to 15thNight
9%42332435%9%50%
1272
16th to endNight
4211312448%65%
1260
July1st to 15thNight
5%213325%5%6%6%58%
1398
16th to endNight
211323346%8%62%
1623
August1st to 15thNight
32133246%5%10%55%
1620
16th to endNight
5%31332345%7%58%
1719
September1st to 15thNight
8%21331435%5%58%
1920
16th to endNight
7%312333345%61%
1980
October1st to 15thNight
15%413323345%52%
2085
16th to endNight
13%414323336%52%
2195
November1st to 15thNight
7%5%15%424346%54%
2275
16th to endNight
7%6%25%5%35%36%7%47%
2487
December1st to 15thNight
10%9%38%5%345%46%37%
2520
16th to endNight
11%10%5%6%6%34345%37%
2856

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
45%5%20%20%9%
1433
16th to endDay
53%5%16%18%6%
1664
February1st to 15thDay
49%419%19%7%
1576
16th to endDay
44%6%17%19%10%1
1569
March1st to 15thDay
44%5%14%23%10%1
1904
16th to endDay
51%6%15%19%6%
2112
April1st to 15thDay
42%313%29%9%
2135
16th to endDay
50%413%19%10%
2340
May1st to 15thDay
41%5%13%24%14%
2331
16th to endDay
44%415%23%10%
2488
June1st to 15thDay
38%6%16%25%11%1
2685
16th to endDay
25%5%19%30%15%3
2700
July1st to 15thDay
27%5%15%33%14%4
2411
16th to endDay
23%5%13%31%22%4
2386
August1st to 15thDay
34%5%16%28%12%2
2326
16th to endDay
28%5%13%32%16%4
2483
September1st to 15thDay
32%412%30%17%2
2038
16th to endDay
27%5%12%34%19%1
1980
October1st to 15thDay
35%310%29%19%2
1863
16th to endDay
35%215%30%13%1
1695
November1st to 15thDay
32%5%16%26%17%2
1583
16th to endDay
39%5%19%24%11%
1470
December1st to 15thDay
47%417%21%7%1
1437
16th to endDay
53%315%19%6%1
1365
January1st to 15thNight
43%5%16%21%11%
2506
16th to endNight
44%418%22%9%
2559
February1st to 15thNight
48%415%21%8%
2288
16th to endNight
37%5%16%25%11%3
1914
March1st to 15thNight
39%415%26%12%1
2055
16th to endNight
43%414%25%9%1
2112
April1st to 15thNight
39%413%28%13%1
1810
16th to endNight
43%413%23%13%1
1620
May1st to 15thNight
34%414%25%18%1
1620
16th to endNight
38%5%15%25%14%1
1630
June1st to 15thNight
31%5%17%26%16%2
1272
16th to endNight
18%413%34%23%4
1260
July1st to 15thNight
24%415%30%16%8%
1318
16th to endNight
18%5%13%31%25%5%
1518
August1st to 15thNight
22%7%16%29%20%3
1610
16th to endNight
24%5%13%29%20%5%
1719
September1st to 15thNight
27%412%28%21%5%
1920
16th to endNight
25%310%33%23%2
1980
October1st to 15thNight
32%49%26%23%3
2085
16th to endNight
34%314%28%18%1
2195
November1st to 15thNight
30%213%25%24%3
2275
16th to endNight
34%318%26%15%1
2487
December1st to 15thNight
46%317%23%7%
2520
16th to endNight
48%414%22%9%
2856

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
10%12%33%37%5%1
90
16th to endDay
19%6%42%21%9%
96
February1st to 15thDay
18%6%40%26%7%
90
16th to endDay
8%13%35%24%16%1
81
March1st to 15thDay
12%12%33%35%5%1
90
16th to endDay
26%7%28%21%14%2
96
April1st to 15thDay
17%11%38%25%6%1
254
16th to endDay
27%13%28%20%8%2
450
May1st to 15thDay
17%9%31%27%12%1
468
16th to endDay
21%6%29%29%10%2
517
June1st to 15thDay
12%6%30%26%20%3
495
16th to endDay
7%5%29%36%19%1
495
July1st to 15thDay
7%223%39%24%2
475
16th to endDay
4125%47%18%1
515
August1st to 15thDay
6%222%40%23%3
493
16th to endDay
9%223%35%25%4
523
September1st to 15thDay
13%430%30%15%5%
193
16th to endDay
16%234%26%18%2
135
October1st to 15thDay
15%8%33%26%14%1
135
16th to endDay
14%440%27%10%4
99
November1st to 15thDay
7%417%42%21%6%
90
16th to endDay
42%7%22%20%7%
90
December1st to 15thDay
28%18%28%13%7%2
90
16th to endDay
18%18%32%27%3
96
January1st to 15thNight
10%12%36%31%7%1
900
16th to endNight
13%10%36%31%6%
960
February1st to 15thNight
16%10%35%29%7%
880
16th to endNight
10%8%36%31%10%1
652
March1st to 15thNight
14%7%35%37%5%
615
16th to endNight
15%8%39%30%6%
576
April1st to 15thNight
14%10%37%31%5%
539
16th to endNight
18%9%35%26%7%1
540
May1st to 15thNight
15%9%32%31%11%
540
16th to endNight
16%431%37%9%
563
June1st to 15thNight
13%329%38%14%
540
16th to endNight
5%225%50%15%
540
July1st to 15thNight
6%219%47%24%
510
16th to endNight
2119%59%16%
564
August1st to 15thNight
5%119%49%24%
539
16th to endNight
6%226%40%22%
573
September1st to 15thNight
10%226%39%17%3
540
16th to endNight
8%6%31%35%15%3
537
October1st to 15thNight
18%8%31%31%10%
645
16th to endNight
16%5%30%35%11%
779
November1st to 15thNight
11%8%32%35%10%1
875
16th to endNight
11%8%36%32%10%
900
December1st to 15thNight
15%10%35%32%5%
900
16th to endNight
17%8%30%32%9%
960
Page generated at 2017-10-17 15:35:30. Version ac04

Copyright 2017 A. Danko


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