Point Petre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Point Petre clear sky chart from 2005-11-05 to 2018-02-14.

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%
15380
13%
48840
10%
15349
42%
15349
17%
34915

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
15%
780
6%
2716
4%
776
18%
776
6%
2281
January16th to endNight
20%
832
8%
2769
5%
832
25%
832
9%
2238
February1st to 15thNight
16%
759
7%
2468
3%
757
22%
757
9%
2006
February16th to endNight
24%
631
11%
1972
5%
631
32%
631
13%
1518
March1st to 15thNight
28%
720
13%
2043
8%
720
32%
720
16%
1534
March16th to endNight
38%
768
20%
2071
10%
768
45%
768
26%
1422
April1st to 15thNight
38%
718
17%
1796
6%
718
42%
718
25%
1294
April16th to endNight
48%
656
19%
1736
10%
656
52%
656
31%
1139
May1st to 15thNight
53%
399
17%
1479
18%
399
57%
399
21%
922
May16th to endNight
62%
374
16%
1497
19%
374
67%
374
24%
865
June1st to 15thNight
56%
360
13%
1440
16%
360
62%
360
20%
901
June16th to endNight
58%
360
12%
1440
19%
360
61%
360
22%
858
July1st to 15thNight
67%
340
16%
1360
25%
340
69%
340
30%
699
July16th to endNight
69%
376
18%
1418
24%
354
71%
354
31%
738
August1st to 15thNight
63%
539
16%
1609
13%
536
65%
536
32%
971
August16th to endNight
66%
691
23%
1837
14%
691
69%
691
40%
1089
September1st to 15thNight
58%
720
20%
1800
11%
720
60%
720
34%
1179
September16th to endNight
57%
717
24%
1976
18%
717
61%
717
33%
1246
October1st to 15thNight
38%
720
14%
2160
13%
720
41%
720
19%
1546
October16th to endNight
25%
768
11%
2337
6%
768
32%
768
13%
1786
November1st to 15thNight
34%
760
16%
2544
15%
760
39%
760
17%
1779
November16th to endNight
23%
780
11%
2730
8%
780
29%
780
10%
2136
December1st to 15thNight
14%
780
5%
2730
2%
780
18%
780
6%
2326
December16th to endNight
13%
832
6%
2912
1%
832
18%
832
6%
2442

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%8%36%5%3445%7%36%
49239
Night
17%9%47%5%3445%6%31%
49011
Cloud CoverDay
15%8%36%5%3445%6%36%
49249
Night
18%10%47%5%3445%6%30%
49016
TransparencyDay
47%413%22%11%1
48928
Night
54%311%19%10%1
48840
SeeingDay
20%417%29%22%6%
5882
Night
23%6%22%27%16%3
15382

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%5%9%6%3345%6%17%
1552
16th to endDay
14%16%6%11%8%38%5%4416%
1804
February1st to 15thDay
15%13%7%14%8%25%35%5%17%
1695
16th to endDay
19%10%49%6%3445%6%24%
1500
March1st to 15thDay
16%9%48%8%3445%7%27%
1904
16th to endDay
16%7%25%42345%5%41%
2152
April1st to 15thDay
19%7%34434347%37%
2152
16th to endDay
17%5%25%5%24446%41%
2235
May1st to 15thDay
13%5%25%5%35%5%5%7%39%
2472
16th to endDay
11%4244345%5%9%44%
2618
June1st to 15thDay
16%5%25%42445%8%39%
2520
16th to endDay
11%5%2442445%10%44%
2520
July1st to 15thDay
8%3134245%5%8%50%
2520
16th to endDay
9%42442447%9%45%
2651
August1st to 15thDay
8%425%5%2446%9%47%
2340
16th to endDay
11%41343346%7%49%
2352
September1st to 15thDay
14%425%424447%45%
2160
16th to endDay
13%32442446%7%46%
1981
October1st to 15thDay
19%6%246%3445%6%35%
1800
16th to endDay
25%9%25%6%2445%6%27%
1886
November1st to 15thDay
15%9%45%5%35%5%5%6%32%
1641
16th to endDay
20%14%5%7%5%3445%5%22%
1560
December1st to 15thDay
21%20%5%10%6%35%345%13%
1560
16th to endDay
23%16%5%9%6%3444416%
1664
January1st to 15thNight
22%15%6%10%6%34445%16%
2716
16th to endNight
16%16%5%9%8%35%45%6%17%
2769
February1st to 15thNight
17%15%7%12%6%33345%18%
2466
16th to endNight
19%10%6%8%6%445%5%6%23%
1972
March1st to 15thNight
20%10%47%6%335%45%29%
2031
16th to endNight
17%7%46%42344440%
2071
April1st to 15thNight
22%7%35%423446%35%
1796
16th to endNight
16%5%25%5%23445%44%
1736
May1st to 15thNight
17%6%25%4245%5%7%38%
1479
16th to endNight
12%4245%35%5%48%42%
1495
June1st to 15thNight
16%426%435%46%8%36%
1440
16th to endNight
10%6%35%425%5%5%9%39%
1440
July1st to 15thNight
6%3244345%5%7%50%
1440
16th to endNight
8%4243245%6%8%49%
1514
August1st to 15thNight
8%5%25%6%3436%8%45%
1620
16th to endNight
7%31443346%8%50%
1837
September1st to 15thNight
14%5%25%423348%45%
1800
16th to endNight
14%42442445%7%46%
1976
October1st to 15thNight
21%7%37%6%33445%33%
2160
16th to endNight
25%9%48%5%34446%24%
2337
November1st to 15thNight
20%8%45%435%45%6%32%
2544
16th to endNight
23%13%47%5%34446%21%
2730
December1st to 15thNight
24%18%6%8%5%34445%14%
2730
16th to endNight
23%16%5%8%6%3445%5%15%
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
19%18%6%10%7%3445%415%
1552
16th to endDay
14%16%8%10%10%46%6%5%314%
1804
February1st to 15thDay
16%14%8%14%8%3444317%
1695
16th to endDay
19%11%5%8%7%35%446%22%
1500
March1st to 15thDay
17%9%5%8%7%35%5%5%6%27%
1915
16th to endDay
17%7%2442345%5%42%
2151
April1st to 15thDay
19%7%34424337%38%
2152
16th to endDay
16%6%245%24446%42%
2235
May1st to 15thDay
12%5%35%5%36%5%5%6%41%
2472
16th to endDay
10%5%244345%5%8%44%
2618
June1st to 15thDay
16%5%2443445%9%39%
2520
16th to endDay
12%42342445%9%45%
2520
July1st to 15thDay
8%31442446%8%51%
2520
16th to endDay
9%42442447%8%46%
2651
August1st to 15thDay
8%4244335%5%8%49%
2340
16th to endDay
12%42432345%8%49%
2352
September1st to 15thDay
15%424424446%46%
2160
16th to endDay
13%425%42445%8%45%
1981
October1st to 15thDay
20%6%345%245%5%6%35%
1800
16th to endDay
26%8%25%6%24446%26%
1886
November1st to 15thDay
15%10%36%6%35%5%5%6%31%
1641
16th to endDay
21%14%6%7%6%24345%22%
1560
December1st to 15thDay
21%20%7%11%6%3434412%
1560
16th to endDay
24%17%7%9%6%34445%13%
1664
January1st to 15thNight
23%17%6%10%7%3434413%
2716
16th to endNight
16%17%6%10%8%4445%5%15%
2769
February1st to 15thNight
17%16%8%12%6%33435%17%
2459
16th to endNight
19%10%7%8%8%4435%5%22%
1972
March1st to 15thNight
20%10%48%6%2443427%
2043
16th to endNight
17%7%46%423245%39%
2071
April1st to 15thNight
22%7%25%424436%35%
1796
16th to endNight
16%5%24422445%44%
1736
May1st to 15thNight
18%6%25%4245%5%7%38%
1479
16th to endNight
12%5%24445%45%7%43%
1495
June1st to 15thNight
15%5%35%4345%6%8%35%
1440
16th to endNight
12%5%25%5%25%5%6%9%39%
1440
July1st to 15thNight
6%324435%45%7%50%
1440
16th to endNight
8%42442446%8%49%
1514
August1st to 15thNight
9%5%25%5%3446%8%44%
1620
16th to endNight
8%3144245%6%9%49%
1837
September1st to 15thNight
15%6%1442445%7%44%
1800
16th to endNight
14%42433345%7%44%
1976
October1st to 15thNight
22%8%36%5%33335%33%
2160
16th to endNight
27%9%47%5%3435%5%24%
2337
November1st to 15thNight
20%9%46%42445%5%31%
2544
16th to endNight
24%15%5%7%5%24445%20%
2730
December1st to 15thNight
25%20%6%8%7%3434411%
2730
16th to endNight
25%17%6%8%6%2345%5%12%
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
69%311%11%3
1553
16th to endDay
72%49%10%3
1804
February1st to 15thDay
70%28%14%3
1697
16th to endDay
61%311%14%7%
1500
March1st to 15thDay
57%314%16%6%1
1915
16th to endDay
43%48%26%14%2
2152
April1st to 15thDay
47%39%23%14%2
2152
16th to endDay
43%38%23%17%3
2235
May1st to 15thDay
41%5%10%24%15%1
2472
16th to endDay
35%5%16%26%13%2
2622
June1st to 15thDay
42%413%25%12%
2520
16th to endDay
35%415%27%15%1
2520
July1st to 15thDay
29%5%12%34%16%1
2371
16th to endDay
33%419%27%13%
2484
August1st to 15thDay
31%420%28%13%1
2327
16th to endDay
32%414%33%13%
2352
September1st to 15thDay
38%413%30%12%1
2160
16th to endDay
36%413%31%13%
1981
October1st to 15thDay
48%411%23%11%
1800
16th to endDay
57%314%18%4
1886
November1st to 15thDay
51%5%14%18%9%1
1641
16th to endDay
64%313%12%5%
1560
December1st to 15thDay
75%311%8%1
1560
16th to endDay
72%310%9%3
1664
January1st to 15thNight
74%37%10%3
2716
16th to endNight
69%310%13%3
2769
February1st to 15thNight
70%38%14%3
2468
16th to endNight
63%211%16%6%
1972
March1st to 15thNight
58%311%18%7%
2043
16th to endNight
47%210%20%16%3
2071
April1st to 15thNight
50%29%20%14%2
1796
16th to endNight
40%411%20%19%3
1736
May1st to 15thNight
44%410%21%16%3
1479
16th to endNight
39%412%25%15%2
1497
June1st to 15thNight
44%5%11%23%14%1
1440
16th to endNight
40%5%13%21%16%2
1440
July1st to 15thNight
30%411%28%23%1
1360
16th to endNight
30%5%12%31%16%3
1418
August1st to 15thNight
35%417%27%13%
1609
16th to endNight
29%414%35%14%1
1837
September1st to 15thNight
39%313%29%12%2
1800
16th to endNight
36%410%31%15%
1976
October1st to 15thNight
54%39%22%10%
2160
16th to endNight
61%313%14%6%
2337
November1st to 15thNight
53%312%18%11%1
2544
16th to endNight
66%311%13%4
2730
December1st to 15thNight
75%310%8%1
2730
16th to endNight
73%310%8%3
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
18%16%27%24%8%3
90
16th to endDay
32%7%30%22%7%
128
February1st to 15thDay
25%14%28%28%3
130
16th to endDay
30%8%23%31%5%
159
March1st to 15thDay
26%6%27%29%9%1
270
16th to endDay
26%325%32%10%2
288
April1st to 15thDay
22%6%26%31%11%2
270
16th to endDay
21%218%31%20%5%
270
May1st to 15thDay
19%214%35%21%5%
288
16th to endDay
14%19%37%27%9%
331
June1st to 15thDay
20%19%33%30%4
315
16th to endDay
18%10%33%33%4
315
July1st to 15thDay
10%17%30%38%11%
305
16th to endDay
11%111%31%34%8%
326
August1st to 15thDay
13%17%30%35%11%
313
16th to endDay
11%211%23%38%11%
332
September1st to 15thDay
15%18%31%26%15%
315
16th to endDay
15%111%30%25%16%
314
October1st to 15thDay
22%416%29%18%8%
315
16th to endDay
29%6%27%24%9%2
327
November1st to 15thDay
20%7%25%28%16%1
205
16th to endDay
25%12%25%22%12%2
90
December1st to 15thDay
27%14%22%26%6%2
90
16th to endDay
37%16%32%12%1
96
January1st to 15thNight
33%12%30%18%6%
780
16th to endNight
25%10%30%25%6%
832
February1st to 15thNight
26%11%33%21%6%
760
16th to endNight
22%8%33%25%8%
631
March1st to 15thNight
26%8%27%29%8%
720
16th to endNight
20%426%30%14%3
768
April1st to 15thNight
24%424%34%11%
718
16th to endNight
19%221%33%19%4
656
May1st to 15thNight
21%14%34%23%5%
399
16th to endNight
12%112%40%26%7%
375
June1st to 15thNight
16%211%37%26%5%
360
16th to endNight
15%210%36%30%4
360
July1st to 15thNight
6%210%35%35%8%
340
16th to endNight
9%111%39%31%7%
376
August1st to 15thNight
12%19%38%30%8%
539
16th to endNight
10%112%31%35%7%
691
September1st to 15thNight
16%312%28%31%7%
720
16th to endNight
16%315%25%25%13%
717
October1st to 15thNight
26%6%19%25%17%5%
720
16th to endNight
30%7%26%25%9%
768
November1st to 15thNight
24%5%28%25%13%1
760
16th to endNight
31%11%25%20%8%1
780
December1st to 15thNight
37%12%28%15%5%
780
16th to endNight
32%11%32%17%41
832
Page generated at 2018-02-15 10:58:41. Version ac04

Copyright 2018 A. Danko


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