Avonmore
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Avonmore clear sky chart from 2005-11-05 to 2018-01-12.

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
30%
15131
13%
48373
8%
15100
36%
15100
16%
34967

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
16%
765
6%
2662
3%
761
20%
761
7%
2185
January16th to endNight
21%
768
9%
2664
6%
768
26%
768
10%
2056
February1st to 15thNight
18%
704
9%
2287
5%
701
24%
701
9%
1807
February16th to endNight
23%
631
13%
1922
7%
631
32%
631
13%
1481
March1st to 15thNight
20%
720
13%
2130
7%
720
27%
720
14%
1621
March16th to endNight
30%
768
20%
2013
9%
768
37%
768
22%
1439
April1st to 15thNight
26%
718
16%
1796
6%
718
30%
718
20%
1343
April16th to endNight
29%
659
17%
1739
6%
659
36%
659
22%
1239
May1st to 15thNight
33%
360
16%
1440
13%
360
42%
360
15%
966
May16th to endNight
36%
374
12%
1497
9%
374
46%
374
18%
937
June1st to 15thNight
37%
360
9%
1440
9%
360
44%
360
13%
994
June16th to endNight
42%
360
9%
1440
12%
360
48%
360
20%
905
July1st to 15thNight
55%
340
14%
1360
20%
340
61%
340
27%
760
July16th to endNight
53%
376
13%
1418
15%
354
58%
354
24%
836
August1st to 15thNight
53%
413
14%
1484
13%
411
58%
411
22%
947
August16th to endNight
52%
738
20%
1884
11%
738
56%
738
35%
1211
September1st to 15thNight
48%
720
15%
1800
8%
720
49%
720
28%
1252
September16th to endNight
47%
717
23%
1947
16%
717
51%
717
32%
1249
October1st to 15thNight
35%
720
17%
2160
11%
720
43%
720
21%
1489
October16th to endNight
24%
768
12%
2423
6%
768
33%
768
13%
1820
November1st to 15thNight
28%
760
16%
2495
11%
760
36%
760
16%
1769
November16th to endNight
21%
780
11%
2730
7%
780
27%
780
10%
2067
December1st to 15thNight
17%
780
7%
2730
2%
780
24%
780
8%
2222
December16th to endNight
13%
832
9%
2912
3%
832
19%
832
7%
2372

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
18%9%36%5%3445%6%32%
48979
Night
18%10%46%5%34446%31%
48542
Cloud CoverDay
19%9%36%5%34446%32%
48988
Night
19%10%47%5%34445%31%
48548
TransparencyDay
52%5%11%19%9%1
48666
Night
53%5%11%18%9%1
48373
SeeingDay
23%10%26%23%11%3
5855
Night
23%9%28%26%10%
15132

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
22%17%6%9%5%2434419%
1520
16th to endDay
14%17%5%7%6%45%5%46%22%
1557
February1st to 15thDay
16%14%5%11%6%35%5%46%21%
1575
16th to endDay
19%13%5%7%6%3434425%
1551
March1st to 15thDay
18%12%49%7%35%33327%
1819
16th to endDay
19%7%345%14445%39%
2211
April1st to 15thDay
24%11%35%5%2224433%
2152
16th to endDay
21%8%35%423345%35%
2229
May1st to 15thDay
20%8%26%42445%6%33%
2511
16th to endDay
17%7%35%5%35%45%6%35%
2618
June1st to 15thDay
23%6%35%5%3445%7%29%
2520
16th to endDay
19%6%245%35%5%7%8%31%
2520
July1st to 15thDay
14%435%425%5%6%8%39%
2520
16th to endDay
14%425%5%36%6%7%8%35%
2654
August1st to 15thDay
12%7%25%6%35%5%6%8%35%
2466
16th to endDay
10%5%245%35%5%5%8%43%
2306
September1st to 15thDay
17%5%25%42336%6%41%
2160
16th to endDay
16%5%14323337%47%
2013
October1st to 15thDay
21%7%26%5%24436%35%
1800
16th to endDay
25%12%36%5%34445%25%
1800
November1st to 15thDay
16%9%46%5%3445%6%32%
1693
16th to endDay
23%12%38%5%34336%26%
1560
December1st to 15thDay
24%15%5%7%7%44435%17%
1560
16th to endDay
24%14%6%8%5%4433321%
1664
January1st to 15thNight
19%17%6%10%7%35%345%17%
2662
16th to endNight
15%16%6%8%6%34345%24%
2664
February1st to 15thNight
14%14%5%12%7%45%45%5%21%
2285
16th to endNight
17%14%5%7%6%3434427%
1922
March1st to 15thNight
20%12%5%7%5%25%32429%
2117
16th to endNight
17%10%35%5%2333439%
2013
April1st to 15thNight
25%7%345%23345%33%
1796
16th to endNight
19%7%35%434336%37%
1739
May1st to 15thNight
21%7%35%425%35%5%34%
1440
16th to endNight
17%7%3433445%7%37%
1495
June1st to 15thNight
22%6%25%6%35%45%8%29%
1440
16th to endNight
17%5%245%2447%8%36%
1440
July1st to 15thNight
10%4134345%7%10%43%
1440
16th to endNight
10%4235%25%6%7%8%42%
1514
August1st to 15thNight
10%8%25%5%35%46%9%38%
1494
16th to endNight
11%5%2442445%8%46%
1884
September1st to 15thNight
15%6%25%43445%6%40%
1800
16th to endNight
16%424324345%48%
1947
October1st to 15thNight
19%8%24424446%37%
2160
16th to endNight
25%9%46%5%34346%26%
2423
November1st to 15thNight
21%10%25%5%2434434%
2495
16th to endNight
22%12%5%8%5%24335%25%
2730
December1st to 15thNight
22%15%5%7%6%25%5%45%19%
2730
16th to endNight
24%15%5%8%5%3444419%
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
22%16%7%8%5%2335%418%
1520
16th to endDay
14%17%6%7%6%45%5%45%21%
1557
February1st to 15thDay
16%15%5%10%8%445%5%420%
1575
16th to endDay
20%14%6%7%7%2433425%
1551
March1st to 15thDay
19%12%5%9%7%3433327%
1829
16th to endDay
20%7%35%423335%38%
2210
April1st to 15thDay
24%10%46%5%22225%33%
2152
16th to endDay
21%8%26%424346%35%
2229
May1st to 15thDay
20%7%34434447%34%
2511
16th to endDay
18%6%35%5%35%5%46%35%
2618
June1st to 15thDay
23%6%35%5%3445%6%30%
2520
16th to endDay
19%5%245%25%6%6%9%31%
2520
July1st to 15thDay
13%5%345%35%5%6%7%39%
2520
16th to endDay
13%5%245%36%6%7%8%36%
2654
August1st to 15thDay
12%6%25%6%46%5%6%7%35%
2466
16th to endDay
10%5%245%35%5%5%7%43%
2306
September1st to 15thDay
17%5%245%3345%7%41%
2160
16th to endDay
15%5%23423336%47%
2013
October1st to 15thDay
21%7%25%5%33446%35%
1800
16th to endDay
27%9%38%5%33435%25%
1800
November1st to 15thDay
16%9%47%5%35%5%47%31%
1693
16th to endDay
23%12%38%5%24335%26%
1560
December1st to 15thDay
23%16%48%7%34445%16%
1560
16th to endDay
25%15%5%7%6%3423321%
1664
January1st to 15thNight
19%18%6%10%6%35%34417%
2662
16th to endNight
14%17%6%9%6%45%34424%
2664
February1st to 15thNight
14%14%6%13%7%3444420%
2278
16th to endNight
18%13%48%7%345%3427%
1922
March1st to 15thNight
21%13%47%5%3432429%
2130
16th to endNight
18%9%46%42324339%
2013
April1st to 15thNight
24%8%35%423435%32%
1796
16th to endNight
20%6%35%434445%37%
1739
May1st to 15thNight
22%7%345%24447%33%
1440
16th to endNight
18%6%25%325%45%7%37%
1495
June1st to 15thNight
22%6%25%6%35%5%6%7%29%
1440
16th to endNight
16%5%35%4245%7%9%35%
1440
July1st to 15thNight
10%3244345%7%9%43%
1440
16th to endNight
10%5%14435%7%7%7%42%
1514
August1st to 15thNight
11%7%26%5%3446%9%38%
1494
16th to endNight
12%4245%2345%7%47%
1884
September1st to 15thNight
16%5%35%424446%41%
1800
16th to endNight
16%5%24324345%48%
1947
October1st to 15thNight
19%7%25%5%24446%36%
2160
16th to endNight
26%9%37%6%34345%26%
2423
November1st to 15thNight
21%9%36%434345%33%
2495
16th to endNight
22%12%47%5%34345%25%
2730
December1st to 15thNight
22%16%5%8%7%25%44419%
2730
16th to endNight
24%16%5%8%6%34345%18%
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
68%49%10%5%
1521
16th to endDay
63%412%12%6%
1557
February1st to 15thDay
65%49%17%2
1577
16th to endDay
62%310%12%9%
1551
March1st to 15thDay
62%311%13%7%1
1829
16th to endDay
48%48%17%15%5%
2211
April1st to 15thDay
55%26%19%12%2
2152
16th to endDay
50%47%18%14%4
2229
May1st to 15thDay
49%5%9%19%13%2
2511
16th to endDay
48%6%11%20%12%1
2622
June1st to 15thDay
53%6%11%20%9%
2520
16th to endDay
47%7%12%20%10%
2520
July1st to 15thDay
39%7%13%28%11%
2371
16th to endDay
42%8%16%23%9%
2487
August1st to 15thDay
45%8%16%21%8%
2452
16th to endDay
37%6%16%28%11%
2306
September1st to 15thDay
41%6%11%26%13%
2160
16th to endDay
38%411%33%11%
2013
October1st to 15thDay
49%5%12%22%9%
1800
16th to endDay
61%5%12%14%5%
1800
November1st to 15thDay
51%6%13%18%8%
1693
16th to endDay
61%5%10%14%6%
1560
December1st to 15thDay
69%5%10%10%2
1560
16th to endDay
68%5%9%10%5%
1664
January1st to 15thNight
70%5%10%9%4
2662
16th to endNight
63%411%13%6%
2664
February1st to 15thNight
65%410%15%4
2287
16th to endNight
60%5%8%16%9%
1922
March1st to 15thNight
60%39%17%8%1
2130
16th to endNight
49%48%18%14%4
2013
April1st to 15thNight
53%47%19%14%
1796
16th to endNight
47%5%7%18%16%3
1739
May1st to 15thNight
50%6%7%15%16%4
1440
16th to endNight
44%6%13%20%13%2
1497
June1st to 15thNight
52%6%12%17%10%
1440
16th to endNight
42%7%14%20%13%
1440
July1st to 15thNight
32%7%14%29%15%
1360
16th to endNight
35%8%15%24%14%
1418
August1st to 15thNight
41%7%17%21%11%
1484
16th to endNight
35%5%14%31%12%
1884
September1st to 15thNight
43%6%11%26%12%
1800
16th to endNight
37%5%10%32%12%
1947
October1st to 15thNight
47%5%10%25%10%
2160
16th to endNight
59%413%17%5%
2423
November1st to 15thNight
53%5%13%17%9%1
2495
16th to endNight
61%5%11%16%5%
2730
December1st to 15thNight
67%6%10%12%3
2730
16th to endNight
68%5%9%11%5%
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
30%14%21%24%8%
82
16th to endDay
37%5%32%17%5%
67
February1st to 15thDay
36%22%28%11%1
90
16th to endDay
30%13%30%21%2
210
March1st to 15thDay
25%13%33%22%5%
270
16th to endDay
23%11%30%22%8%2
288
April1st to 15thDay
32%14%27%18%7%1
270
16th to endDay
22%15%23%22%10%4
270
May1st to 15thDay
27%9%29%17%12%3
288
16th to endDay
19%15%32%17%12%1
331
June1st to 15thDay
27%7%28%24%7%3
315
16th to endDay
23%7%28%26%12%2
315
July1st to 15thDay
15%6%25%32%17%4
305
16th to endDay
15%423%34%18%3
326
August1st to 15thDay
16%421%34%16%5%
313
16th to endDay
13%5%22%31%15%12%
332
September1st to 15thDay
17%6%21%22%19%13%
315
16th to endDay
14%8%24%21%21%9%
314
October1st to 15thDay
24%9%26%22%13%4
315
16th to endDay
33%11%26%20%7%
306
November1st to 15thDay
21%13%31%19%12%1
257
16th to endDay
30%21%23%20%5%
90
December1st to 15thDay
25%20%30%17%6%
90
16th to endDay
38%26%25%9%1
96
January1st to 15thNight
27%15%32%19%5%
765
16th to endNight
22%13%32%25%6%
768
February1st to 15thNight
22%15%34%24%3
704
16th to endNight
25%10%33%24%5%
631
March1st to 15thNight
27%13%33%21%4
720
16th to endNight
21%10%30%28%8%
768
April1st to 15thNight
27%10%30%26%5%
718
16th to endNight
24%10%31%24%8%
659
May1st to 15thNight
27%429%27%8%1
360
16th to endNight
18%7%34%28%10%
375
June1st to 15thNight
24%6%23%37%8%
360
16th to endNight
16%229%34%14%1
360
July1st to 15thNight
11%324%40%19%
340
16th to endNight
11%226%42%15%1
376
August1st to 15thNight
14%418%41%19%2
413
16th to endNight
13%322%36%21%1
738
September1st to 15thNight
19%421%35%16%2
720
16th to endNight
19%5%23%23%24%2
717
October1st to 15thNight
23%6%30%26%13%
720
16th to endNight
30%12%25%23%7%
768
November1st to 15thNight
26%10%28%22%10%
760
16th to endNight
28%15%27%19%9%
780
December1st to 15thNight
30%14%30%20%3
780
16th to endNight
32%13%32%17%3
832
Page generated at 2018-01-12 22:01:29. Version ac04

Copyright 2018 A. Danko


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