This page made possible by the sponsorship of: Blake Nancarrow.

Fingal Wildlife Centre
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fingal Wildlife Centre clear sky chart from 2005-11-06 to 2024-01-31.

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
38%
23144
16%
74621
11%
23097
44%
23097
20%
51108

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 10thNight
16%
758
13%
2497
5%
757
25%
757
11%
1910
January11th to 20thNight
16%
760
8%
2470
4%
760
21%
760
8%
1988
January21st to endNight
20%
835
11%
2711
5%
835
27%
835
12%
2090
February1st to 10thNight
19%
720
9%
2340
3%
720
26%
720
11%
1819
February11th to 20thNight
22%
700
13%
2261
5%
699
31%
699
13%
1670
February21st to endNight
21%
592
15%
1776
5%
592
32%
592
15%
1338
March1st to 10thNight
29%
720
18%
2032
9%
720
36%
720
20%
1431
March11th to 20thNight
32%
720
20%
1980
10%
720
39%
720
22%
1375
March21st to endNight
33%
792
19%
2178
10%
792
40%
792
21%
1562
April1st to 10thNight
34%
720
16%
1921
8%
720
39%
720
24%
1350
April11th to 20thNight
37%
565
21%
1629
11%
565
44%
565
24%
1096
April21st to endNight
37%
540
19%
1620
8%
540
44%
540
24%
1072
May1st to 10thNight
42%
540
15%
1620
10%
540
45%
540
23%
1079
May11th to 20thNight
49%
531
19%
1592
14%
531
55%
531
26%
1035
May21st to endNight
58%
414
17%
1577
18%
414
64%
414
30%
856
June1st to 10thNight
55%
360
16%
1440
19%
360
62%
360
27%
788
June11th to 20thNight
57%
360
20%
1305
21%
360
65%
360
30%
729
June21st to endNight
58%
360
21%
1260
21%
360
66%
360
29%
728
July1st to 10thNight
71%
369
21%
1244
24%
369
74%
369
38%
664
July11th to 20thNight
65%
522
18%
1542
18%
522
67%
522
36%
886
July21st to endNight
67%
591
18%
1672
16%
558
70%
558
36%
960
August1st to 10thNight
71%
537
20%
1600
17%
534
72%
534
37%
920
August11th to 20thNight
70%
534
23%
1598
18%
534
73%
534
37%
908
August21st to endNight
62%
607
24%
1795
17%
607
67%
607
37%
1056
September1st to 10thNight
58%
720
20%
1856
12%
720
62%
720
35%
1184
September11th to 20thNight
64%
720
28%
1980
21%
720
68%
720
39%
1156
September21st to endNight
50%
720
21%
1980
15%
720
54%
720
29%
1293
October1st to 10thNight
47%
720
20%
2115
18%
720
52%
720
28%
1324
October11th to 20thNight
34%
720
17%
2160
11%
720
44%
720
22%
1472
October21st to endNight
27%
792
17%
2402
11%
792
35%
792
17%
1727
November1st to 10thNight
40%
740
22%
2406
17%
740
49%
740
24%
1509
November11th to 20thNight
25%
760
16%
2598
9%
760
35%
760
16%
1759
November21st to endNight
25%
760
11%
2660
7%
760
31%
760
13%
1917
December1st to 10thNight
18%
760
10%
2660
4%
760
25%
760
10%
1993
December11th to 20thNight
17%
760
8%
3268
3%
759
25%
759
8%
2450
December21st to endNight
17%
825
5%
4876
2%
817
24%
817
4%
4014

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
14%8%47%6%45%5%6%8%33%
75278
Night
16%9%47%6%35%5%5%7%34%
74843
TransparencyDay
48%5%13%21%11%1
74989
Night
50%412%21%12%1
74652
SeeingDay
17%6%25%29%17%6%
13891
Night
20%6%26%30%15%2
23162

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 10thDay
17%14%5%9%9%46%6%45%19%
1663
11th to 20thDay
17%14%6%12%9%5%5%45%6%17%
1710
21st to endDay
18%15%7%10%9%45%6%5%5%16%
1872
February1st to 10thDay
16%15%5%11%9%46%45%6%19%
1620
11th to 20thDay
16%11%6%10%8%6%6%446%23%
1582
21st to endDay
18%10%410%7%46%5%6%5%24%
1480
March1st to 10thDay
16%10%5%8%7%46%5%5%6%28%
1926
11th to 20thDay
14%10%5%8%7%46%5%5%7%30%
1980
21st to endDay
20%9%48%6%45%45%6%30%
2178
April1st to 10thDay
15%10%47%7%45%5%6%8%31%
2038
11th to 20thDay
17%10%46%6%35%45%7%33%
2294
21st to endDay
19%8%46%5%4445%6%35%
2340
May1st to 10thDay
15%7%36%6%35%5%6%9%34%
2340
11th to 20thDay
15%7%46%6%35%5%5%8%36%
2301
21st to endDay
10%5%25%445%6%7%9%43%
2698
June1st to 10thDay
11%5%26%6%35%6%6%8%42%
2520
11th to 20thDay
9%5%35%5%45%7%8%8%41%
2650
21st to endDay
10%5%25%5%35%5%8%9%43%
2700
July1st to 10thDay
8%4245%36%5%5%10%48%
2675
11th to 20thDay
9%5%25%5%35%5%7%11%42%
2361
21st to endDay
8%425%6%35%7%8%11%41%
2547
August1st to 10thDay
8%425%5%46%6%8%9%44%
2327
11th to 20thDay
8%425%7%46%7%8%11%38%
2303
21st to endDay
10%5%36%5%45%46%8%44%
2543
September1st to 10thDay
10%5%25%5%46%5%7%8%43%
2101
11th to 20thDay
10%5%245%35%6%6%8%46%
1980
21st to endDay
18%5%245%345%7%8%38%
1980
October1st to 10thDay
15%7%26%6%346%5%8%38%
1843
11th to 20thDay
19%9%37%6%35%6%5%8%30%
1800
21st to endDay
24%10%47%7%45%45%6%25%
1951
November1st to 10thDay
13%8%37%6%46%5%6%8%34%
1672
11th to 20thDay
16%9%47%6%45%6%6%7%31%
1581
21st to endDay
20%11%5%8%7%46%5%6%7%21%
1520
December1st to 10thDay
18%13%5%9%8%45%46%7%20%
1520
11th to 20thDay
20%13%6%10%8%35%5%6%6%18%
1910
21st to endDay
29%19%6%9%7%34445%11%
2772
January1st to 10thNight
19%12%6%9%7%36%5%5%6%22%
2497
11th to 20thNight
21%17%6%9%6%45%5%5%5%18%
2470
21st to endNight
16%15%6%10%8%35%5%5%5%22%
2711
February1st to 10thNight
18%15%5%9%7%445%5%6%22%
2340
11th to 20thNight
18%12%6%7%7%45%5%5%6%26%
2261
21st to endNight
20%11%48%9%35%5%46%26%
1776
March1st to 10thNight
16%7%47%7%45%5%5%7%31%
2032
11th to 20thNight
16%8%46%6%45%35%7%36%
1980
21st to endNight
19%9%47%5%345%5%6%34%
2178
April1st to 10thNight
18%8%46%5%35%45%6%35%
1921
11th to 20thNight
17%7%36%5%36%45%7%37%
1629
21st to endNight
15%8%36%6%35%45%6%38%
1620
May1st to 10thNight
17%8%35%5%345%6%9%33%
1620
11th to 20thNight
14%5%36%7%45%5%5%6%40%
1592
21st to endNight
10%4344246%7%8%48%
1576
June1st to 10thNight
12%4246%245%6%9%46%
1440
11th to 20thNight
10%5%25%445%5%7%9%44%
1305
21st to endNight
11%4145%445%6%8%48%
1260
July1st to 10thNight
6%3246%34439%56%
1280
11th to 20thNight
10%425%4345%5%10%49%
1594
21st to endNight
8%4245%35%5%8%9%48%
1771
August1st to 10thNight
6%424446%5%8%9%48%
1611
11th to 20thNight
7%4245%35%6%7%9%49%
1598
21st to endNight
9%4245%35%5%5%9%50%
1795
September1st to 10thNight
9%6%36%5%35%5%6%6%47%
1856
11th to 20thNight
10%4245%35%45%6%53%
1980
21st to endNight
15%5%26%5%445%6%6%42%
1980
October1st to 10thNight
15%5%26%5%3445%7%44%
2115
11th to 20thNight
18%8%47%5%345%5%7%36%
2160
21st to endNight
22%8%46%5%345%6%5%30%
2402
November1st to 10thNight
14%7%35%435%5%5%8%41%
2406
11th to 20thNight
16%8%36%6%46%5%6%7%32%
2598
21st to endNight
21%11%47%6%345%6%6%27%
2660
December1st to 10thNight
20%13%6%8%6%35%45%7%22%
2660
11th to 20thNight
17%16%6%8%7%45%5%46%23%
3285
21st to endNight
28%17%6%9%6%35%445%14%
4884

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 10thDay
67%411%13%6%
1664
11th to 20thDay
69%311%12%4
1710
21st to endDay
69%39%12%6%1
1872
February1st to 10thDay
67%310%13%6%1
1620
11th to 20thDay
62%5%9%16%8%1
1591
21st to endDay
60%5%11%17%6%1
1480
March1st to 10thDay
55%412%19%8%1
1926
11th to 20thDay
54%411%19%10%2
1980
21st to endDay
55%49%20%11%1
2178
April1st to 10thDay
51%311%21%13%
2038
11th to 20thDay
49%412%19%14%1
2294
21st to endDay
49%412%20%12%2
2340
May1st to 10thDay
46%411%24%12%2
2340
11th to 20thDay
46%5%13%21%14%2
2305
21st to endDay
36%5%17%25%16%2
2698
June1st to 10thDay
39%413%28%13%2
2520
11th to 20thDay
37%7%14%23%17%2
2650
21st to endDay
34%6%15%28%17%1
2700
July1st to 10thDay
31%6%12%29%19%3
2602
11th to 20thDay
34%5%17%28%15%2
2290
21st to endDay
33%6%18%25%15%2
2405
August1st to 10thDay
33%6%17%30%13%1
2314
11th to 20thDay
36%5%19%26%12%1
2303
21st to endDay
37%414%29%15%2
2543
September1st to 10thDay
37%5%17%25%14%2
2101
11th to 20thDay
34%415%32%15%
1980
21st to endDay
42%5%13%26%13%1
1980
October1st to 10thDay
44%5%13%22%14%1
1843
11th to 20thDay
51%5%14%21%9%1
1800
21st to endDay
60%413%16%7%
1951
November1st to 10thDay
47%5%12%24%9%2
1672
11th to 20thDay
51%418%16%10%1
1581
21st to endDay
64%314%15%3
1520
December1st to 10thDay
63%5%13%15%4
1520
11th to 20thDay
67%315%10%4
1906
21st to endDay
77%311%7%2
2772
January1st to 10thNight
64%310%14%9%
2497
11th to 20thNight
70%310%12%5%
2470
21st to endNight
64%312%15%5%1
2711
February1st to 10thNight
63%5%11%15%6%1
2340
11th to 20thNight
59%310%18%9%1
2263
21st to endNight
59%39%20%8%1
1776
March1st to 10thNight
51%411%23%11%1
2032
11th to 20thNight
49%49%23%14%2
1980
21st to endNight
51%47%22%12%3
2178
April1st to 10thNight
49%49%21%14%2
1921
11th to 20thNight
46%39%23%17%2
1629
21st to endNight
46%310%21%16%3
1620
May1st to 10thNight
48%310%22%13%4
1620
11th to 20thNight
44%310%23%15%4
1593
21st to endNight
34%415%26%18%3
1577
June1st to 10thNight
36%411%29%17%3
1440
11th to 20thNight
35%314%26%19%3
1305
21st to endNight
35%6%11%26%21%1
1260
July1st to 10thNight
30%38%32%22%5%
1244
11th to 20thNight
32%412%30%18%3
1542
21st to endNight
31%6%14%26%20%3
1672
August1st to 10thNight
30%5%15%34%14%2
1600
11th to 20thNight
31%415%33%15%2
1598
21st to endNight
33%413%30%18%2
1795
September1st to 10thNight
36%5%12%29%15%2
1856
11th to 20thNight
32%312%32%19%1
1980
21st to endNight
42%313%27%14%1
1980
October1st to 10thNight
40%412%26%18%1
2115
11th to 20thNight
48%312%22%13%
2160
21st to endNight
55%311%19%11%1
2402
November1st to 10thNight
42%312%26%15%1
2406
11th to 20thNight
52%313%21%10%1
2598
21st to endNight
59%217%17%5%1
2660
December1st to 10thNight
63%214%16%5%
2660
11th to 20thNight
63%314%14%5%
3288
21st to endNight
75%312%8%2
4884

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 10thDay
24%12%34%22%6%2
249
11th to 20thDay
24%9%43%17%6%2
270
21st to endDay
28%9%31%27%41
294
February1st to 10thDay
23%13%40%22%2
240
11th to 20thDay
23%14%37%23%4
240
21st to endDay
24%19%36%19%2
198
March1st to 10thDay
19%11%36%25%10%
366
11th to 20thDay
17%11%31%31%9%1
420
21st to endDay
25%8%32%26%8%1
462
April1st to 10thDay
19%8%33%30%9%2
420
11th to 20thDay
24%7%33%21%10%5%
412
21st to endDay
23%5%32%26%11%3
420
May1st to 10thDay
23%428%29%13%4
423
11th to 20thDay
17%423%30%19%7%
447
21st to endDay
12%222%31%22%11%
485
June1st to 10thDay
12%226%37%17%7%
450
11th to 20thDay
10%422%35%24%5%
580
21st to endDay
12%223%37%21%5%
630
July1st to 10thDay
8%116%33%28%13%
621
11th to 20thDay
14%217%30%26%12%
463
21st to endDay
9%114%36%29%10%
488
August1st to 10thDay
8%115%33%25%18%
446
11th to 20thDay
10%112%36%28%13%
439
21st to endDay
13%113%34%29%10%
495
September1st to 10thDay
13%215%33%26%11%
450
11th to 20thDay
10%114%26%32%16%
450
21st to endDay
19%420%26%22%8%
450
October1st to 10thDay
19%422%24%22%9%
450
11th to 20thDay
21%9%32%27%9%2
450
21st to endDay
27%9%32%24%8%1
466
November1st to 10thDay
17%10%34%22%13%4
270
11th to 20thDay
21%15%33%22%5%3
209
21st to endDay
24%9%37%24%4
180
December1st to 10thDay
25%13%35%19%7%1
180
11th to 20thDay
29%19%29%17%6%
180
21st to endDay
30%13%31%21%41
198
January1st to 10thNight
26%13%36%18%6%1
760
11th to 20thNight
30%12%28%23%6%
760
21st to endNight
24%8%33%28%7%
835
February1st to 10thNight
27%8%34%27%4
720
11th to 20thNight
24%9%33%28%5%1
703
21st to endNight
24%9%38%25%4
592
March1st to 10thNight
20%7%34%31%8%
720
11th to 20thNight
21%6%33%30%9%1
720
21st to endNight
23%6%29%30%11%1
792
April1st to 10thNight
22%7%29%32%8%1
720
11th to 20thNight
21%5%32%29%12%1
565
21st to endNight
20%331%34%12%1
540
May1st to 10thNight
19%326%35%15%2
540
11th to 20thNight
15%322%42%16%3
531
21st to endNight
13%218%35%27%4
416
June1st to 10thNight
16%122%39%20%3
360
11th to 20thNight
13%119%40%25%2
360
21st to endNight
12%119%44%22%2
360
July1st to 10thNight
7%112%40%34%6%
369
11th to 20thNight
15%110%41%27%6%
522
21st to endNight
10%112%45%29%4
591
August1st to 10thNight
9%111%39%35%6%
537
11th to 20thNight
8%10%37%38%7%
534
21st to endNight
12%15%37%29%5%
607
September1st to 10thNight
11%317%32%28%9%
720
11th to 20thNight
12%313%33%32%7%
720
21st to endNight
18%320%33%19%8%
720
October1st to 10thNight
18%421%33%19%5%
720
11th to 20thNight
21%8%28%28%13%1
720
21st to endNight
27%8%31%28%6%
792
November1st to 10thNight
18%9%25%31%15%1
740
11th to 20thNight
22%12%34%22%8%2
760
21st to endNight
28%11%29%25%8%
760
December1st to 10thNight
28%13%32%19%6%1
760
11th to 20thNight
26%15%33%21%5%
760
21st to endNight
32%10%30%25%3
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