Wren Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wren Park clear sky chart from 2005-11-06 to 2024-03-08.

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
33%
22736
9%
81023
7%
22608
36%
22608
12%
61453

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%
845
5%
4706
5%
816
19%
816
3%
4103
January11th to 20thNight
22%
828
16%
4534
5%
804
26%
804
6%
3125
January21st to endNight
20%
836
5%
4862
6%
814
25%
814
4%
4251
February1st to 10thNight
17%
760
8%
2470
2%
760
24%
760
7%
2042
February11th to 20thNight
19%
740
9%
2404
4%
740
25%
740
9%
1949
February21st to endNight
23%
628
12%
2001
7%
628
30%
628
10%
1570
March1st to 10thNight
27%
750
8%
2215
6%
750
30%
750
12%
1748
March11th to 20thNight
23%
720
9%
1980
5%
720
26%
720
11%
1626
March21st to endNight
24%
792
5%
2102
2%
792
25%
792
10%
1767
April1st to 10thNight
26%
720
6%
1800
3%
720
27%
720
13%
1496
April11th to 20thNight
26%
651
10%
1719
5%
651
29%
651
14%
1371
April21st to endNight
31%
464
7%
1544
5%
464
34%
464
11%
1201
May1st to 10thNight
43%
360
10%
1440
15%
360
45%
360
16%
967
May11th to 20thNight
54%
354
9%
1416
17%
354
55%
354
16%
949
May21st to endNight
50%
388
6%
1544
10%
388
51%
388
16%
1045
June1st to 10thNight
43%
360
3%
1260
2%
360
43%
360
15%
925
June11th to 20thNight
41%
360
2%
1260
1%
360
42%
360
12%
965
June21st to endNight
56%
360
6%
1260
3%
360
57%
360
24%
780
July1st to 10thNight
65%
350
8%
1225
8%
350
65%
350
27%
727
July11th to 20thNight
66%
348
14%
1218
18%
348
68%
348
33%
669
July21st to endNight
80%
394
18%
1476
29%
372
83%
372
44%
639
August1st to 10thNight
74%
358
17%
1424
25%
356
76%
356
35%
683
August11th to 20thNight
77%
521
22%
1589
22%
521
78%
521
45%
811
August21st to endNight
62%
672
19%
1860
15%
672
63%
672
32%
1154
September1st to 10thNight
61%
720
17%
1800
10%
720
62%
720
36%
1148
September11th to 20thNight
50%
720
18%
1800
10%
720
52%
720
27%
1261
September21st to endNight
45%
720
16%
2055
13%
720
47%
720
22%
1450
October1st to 10thNight
40%
720
10%
2160
9%
720
43%
720
19%
1543
October11th to 20thNight
32%
720
10%
2160
9%
720
35%
720
15%
1641
October21st to endNight
26%
792
10%
2514
7%
792
31%
792
12%
1922
November1st to 10thNight
18%
740
6%
2590
4%
740
22%
740
7%
2132
November11th to 20thNight
18%
760
8%
2660
4%
760
23%
760
8%
2161
November21st to endNight
18%
760
6%
2660
2%
760
23%
760
7%
2189
December1st to 10thNight
24%
760
11%
2660
6%
760
31%
760
11%
2057
December11th to 20thNight
12%
832
4%
3472
2%
831
15%
831
4%
3003
December21st to endNight
10%
933
4%
5183
3%
905
15%
905
3%
4383

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
31%9%35%5%34445%29%
78151
Night
34%9%35%423345%27%
81355
TransparencyDay
58%6%12%16%7%1
77863
Night
60%6%12%14%7%2
81223
SeeingDay
32%11%23%22%10%2
14267
Night
36%7%17%23%15%1
22752

By Month

Percentage Cloud Cover NW (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
48%13%36%43333211%
2219
11th to 20thDay
32%12%5%6%42322426%
2259
21st to endDay
57%11%3432222312%
2794
February1st to 10thDay
40%11%46%6%33345%17%
1705
11th to 20thDay
36%11%36%5%2333422%
1665
21st to endDay
31%16%46%6%3344420%
1452
March1st to 10thDay
33%16%45%5%3443320%
1902
11th to 20thDay
39%13%35%5%3433318%
1980
21st to endDay
35%13%37%6%2444417%
2254
April1st to 10thDay
34%11%46%7%34445%18%
2160
11th to 20thDay
30%10%47%6%45%445%20%
2190
21st to endDay
30%10%46%6%3445%5%21%
2416
May1st to 10thDay
26%8%36%6%35%445%30%
2520
11th to 20thDay
23%8%36%5%3445%7%30%
2477
21st to endDay
29%9%47%5%33445%28%
2727
June1st to 10thDay
31%7%35%6%34446%27%
2700
11th to 20thDay
33%8%47%6%45%45%5%20%
2700
21st to endDay
22%7%35%5%345%46%35%
2700
July1st to 10thDay
18%5%25%42445%5%47%
2700
11th to 20thDay
15%5%24324347%49%
2700
21st to endDay
13%312323347%60%
2751
August1st to 10thDay
16%424323445%53%
2507
11th to 20thDay
12%42342346%6%55%
2307
21st to endDay
19%5%245%3445%8%42%
2495
September1st to 10thDay
19%7%25%423336%46%
2160
11th to 20thDay
23%6%35%5%2434439%
2160
21st to endDay
29%7%25%413445%36%
1902
October1st to 10thDay
28%9%25%423436%35%
1800
11th to 20thDay
37%8%35%5%24346%25%
1800
21st to endDay
41%8%35%322346%24%
1840
November1st to 10thDay
46%8%35%5%3333417%
1488
11th to 20thDay
43%11%35%32322323%
1520
21st to endDay
44%9%35%42344319%
1520
December1st to 10thDay
38%13%4332234326%
1520
11th to 20thDay
41%13%46%42432317%
1719
21st to endDay
44%14%47%5%3233411%
2442
January1st to 10thNight
47%15%36%42233313%
4726
11th to 20thNight
35%9%33423346%28%
4636
21st to endNight
54%11%35%31222313%
4862
February1st to 10thNight
40%10%36%5%23345%20%
2470
11th to 20thNight
34%15%35%5%2333422%
2402
21st to endNight
33%12%35%433345%25%
2001
March1st to 10thNight
32%12%45%5%34445%23%
2215
11th to 20thNight
38%11%36%5%3344420%
1979
21st to endNight
39%10%35%5%3445%319%
2102
April1st to 10thNight
32%11%37%6%34445%21%
1800
11th to 20thNight
27%10%46%6%445%45%24%
1719
21st to endNight
34%8%36%6%345%45%22%
1544
May1st to 10thNight
23%9%36%334436%37%
1440
11th to 20thNight
21%5%26%5%35%7%6%6%33%
1416
21st to endNight
23%6%36%5%2445%7%35%
1544
June1st to 10thNight
26%8%37%5%345%45%30%
1260
11th to 20thNight
24%9%48%6%345%6%6%24%
1260
21st to endNight
19%6%25%5%2445%7%42%
1260
July1st to 10thNight
13%6%35%424435%51%
1260
11th to 20thNight
11%423332446%57%
1260
21st to endNight
7%212324346%66%
1563
August1st to 10thNight
12%42221335%6%60%
1432
11th to 20thNight
8%31332246%7%62%
1589
21st to endNight
13%5%25%5%345%7%8%45%
1860
September1st to 10thNight
13%5%1443335%6%52%
1800
11th to 20thNight
24%5%245%23346%43%
1800
21st to endNight
26%7%25%423445%38%
2055
October1st to 10thNight
25%7%245%4443437%
2160
11th to 20thNight
35%8%25%433345%29%
2160
21st to endNight
38%7%25%43334427%
2514
November1st to 10thNight
46%9%25%42343418%
2590
11th to 20thNight
44%9%35%42333322%
2660
21st to endNight
44%10%25%43333321%
2660
December1st to 10thNight
36%10%24434345%26%
2660
11th to 20thNight
48%12%35%42432314%
3482
21st to endNight
47%12%36%42323314%
5214

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
76%8%6%6%31
2219
11th to 20thDay
63%5%6%14%7%4
2280
21st to endDay
79%5%6%8%31
2794
February1st to 10thDay
71%5%9%7%6%2
1705
11th to 20thDay
66%6%8%11%8%2
1674
21st to endDay
69%49%11%5%2
1452
March1st to 10thDay
68%5%10%11%41
1902
11th to 20thDay
71%5%7%12%5%1
1980
21st to endDay
72%5%10%11%2
2254
April1st to 10thDay
69%6%12%10%2
2160
11th to 20thDay
66%5%8%11%7%2
2190
21st to endDay
64%6%12%10%7%1
2416
May1st to 10thDay
56%6%15%16%7%1
2520
11th to 20thDay
53%8%17%16%7%
2480
21st to endDay
59%7%16%16%2
2728
June1st to 10thDay
60%5%15%13%5%2
2700
11th to 20thDay
66%5%15%10%3
2700
21st to endDay
49%7%16%18%8%1
2700
July1st to 10thDay
39%7%14%25%12%2
2626
11th to 20thDay
36%5%17%30%10%2
2619
21st to endDay
25%5%17%35%15%4
2598
August1st to 10thDay
32%6%19%30%11%2
2490
11th to 20thDay
29%6%20%29%14%2
2307
21st to endDay
40%6%19%27%7%1
2495
September1st to 10thDay
41%6%14%23%12%4
2160
11th to 20thDay
50%5%10%17%15%3
2160
21st to endDay
51%6%14%17%10%2
1902
October1st to 10thDay
53%5%14%17%11%1
1800
11th to 20thDay
61%5%12%16%41
1800
21st to endDay
63%5%10%12%8%1
1840
November1st to 10thDay
72%49%10%31
1488
11th to 20thDay
71%38%9%6%2
1520
21st to endDay
69%5%6%11%8%2
1520
December1st to 10thDay
66%5%8%11%10%1
1520
11th to 20thDay
70%6%8%11%31
1722
21st to endDay
74%10%7%7%21
2442
January1st to 10thNight
76%7%5%9%2
4726
11th to 20thNight
57%5%9%16%9%5%
4677
21st to endNight
77%5%6%8%31
4862
February1st to 10thNight
71%49%9%42
2470
11th to 20thNight
68%5%8%11%7%2
2404
21st to endNight
65%49%14%6%2
2001
March1st to 10thNight
61%7%13%12%6%1
2215
11th to 20thNight
66%5%10%12%6%1
1980
21st to endNight
69%5%15%9%2
2102
April1st to 10thNight
66%6%13%13%2
1800
11th to 20thNight
61%6%11%13%7%2
1719
21st to endNight
64%5%12%12%6%1
1544
May1st to 10thNight
49%7%19%17%7%1
1440
11th to 20thNight
49%7%21%17%6%
1416
21st to endNight
50%7%19%19%5%
1544
June1st to 10thNight
56%6%17%13%5%2
1260
11th to 20thNight
59%8%18%12%3
1260
21st to endNight
40%6%23%20%7%3
1260
July1st to 10thNight
36%7%13%26%14%4
1225
11th to 20thNight
30%6%18%31%13%2
1218
21st to endNight
19%5%15%35%21%5%
1476
August1st to 10thNight
26%5%19%31%17%3
1424
11th to 20thNight
22%6%23%30%14%6%
1589
21st to endNight
37%5%19%29%10%1
1860
September1st to 10thNight
33%7%18%25%14%4
1800
11th to 20thNight
44%6%13%17%15%4
1800
21st to endNight
48%7%15%19%9%2
2055
October1st to 10thNight
51%6%14%19%9%1
2160
11th to 20thNight
59%5%14%15%6%1
2160
21st to endNight
60%6%11%14%9%
2514
November1st to 10thNight
70%5%10%11%31
2590
11th to 20thNight
69%5%10%8%6%2
2660
21st to endNight
70%5%8%8%8%2
2660
December1st to 10thNight
61%7%11%12%8%1
2660
11th to 20thNight
76%6%7%6%31
3478
21st to endNight
74%6%8%7%4
5214

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
49%14%14%10%9%3
180
11th to 20thDay
49%11%18%14%6%1
180
21st to endDay
45%14%20%14%7%1
198
February1st to 10thDay
47%13%19%14%42
365
11th to 20thDay
42%14%23%16%5%1
365
21st to endDay
41%16%25%12%5%1
326
March1st to 10thDay
41%15%20%18%6%
449
11th to 20thDay
41%12%19%18%8%1
420
21st to endDay
44%16%19%15%6%1
462
April1st to 10thDay
40%15%20%17%7%1
420
11th to 20thDay
33%16%24%17%9%1
412
21st to endDay
32%16%26%16%10%1
420
May1st to 10thDay
26%12%32%22%7%1
423
11th to 20thDay
28%9%22%26%10%4
448
21st to endDay
29%11%25%22%9%4
489
June1st to 10thDay
29%13%26%22%7%2
630
11th to 20thDay
29%15%28%21%5%1
630
21st to endDay
24%10%24%27%13%2
630
July1st to 10thDay
19%7%29%32%10%2
621
11th to 20thDay
15%10%27%35%11%3
618
21st to endDay
11%5%25%38%15%6%
497
August1st to 10thDay
16%6%22%33%16%7%
447
11th to 20thDay
12%424%34%21%6%
437
21st to endDay
20%11%24%28%13%4
495
September1st to 10thDay
24%9%26%28%12%2
450
11th to 20thDay
26%9%21%28%15%2
450
21st to endDay
30%8%20%26%12%4
450
October1st to 10thDay
33%8%22%18%16%2
450
11th to 20thDay
41%8%16%19%15%2
450
21st to endDay
43%10%19%17%9%2
357
November1st to 10thDay
44%16%18%14%7%
180
11th to 20thDay
52%7%14%10%14%3
180
21st to endDay
50%7%20%8%11%4
180
December1st to 10thDay
49%13%13%9%13%3
180
11th to 20thDay
54%8%17%16%5%1
180
21st to endDay
52%11%20%14%3
198
January1st to 10thNight
54%11%15%14%6%1
850
11th to 20thNight
49%8%17%20%6%
832
21st to endNight
46%10%19%19%7%
836
February1st to 10thNight
46%11%21%17%5%
760
11th to 20thNight
44%10%21%21%5%
744
21st to endNight
39%11%23%20%7%
628
March1st to 10thNight
35%12%20%21%12%
750
11th to 20thNight
44%9%19%19%8%
720
21st to endNight
42%9%19%21%9%
792
April1st to 10thNight
39%7%19%25%9%1
720
11th to 20thNight
31%10%26%23%10%
651
21st to endNight
38%6%18%27%11%1
464
May1st to 10thNight
26%7%16%30%20%1
360
11th to 20thNight
23%310%36%26%3
354
21st to endNight
26%412%32%25%1
389
June1st to 10thNight
28%5%17%29%19%2
360
11th to 20thNight
28%6%17%29%18%3
360
21st to endNight
21%412%33%28%3
360
July1st to 10thNight
14%5%11%30%38%2
350
11th to 20thNight
12%411%31%36%6%
348
21st to endNight
8%25%32%47%6%
394
August1st to 10thNight
13%16%25%48%8%
358
11th to 20thNight
9%17%30%44%7%
521
21st to endNight
15%311%31%36%3
672
September1st to 10thNight
16%215%37%28%2
720
11th to 20thNight
25%414%23%29%5%
720
21st to endNight
29%6%14%30%20%1
720
October1st to 10thNight
29%5%18%25%21%1
720
11th to 20thNight
40%418%21%16%1
720
21st to endNight
41%10%20%21%7%1
792
November1st to 10thNight
50%10%19%19%2
740
11th to 20thNight
50%8%19%14%7%1
760
21st to endNight
48%10%18%15%8%1
760
December1st to 10thNight
39%9%22%22%8%
760
11th to 20thNight
53%9%21%14%3
832
21st to endNight
52%10%24%11%2
935
Page generated at 2024-03-05 04:24:03. Version ac07

Copyright © 2024 Attilla Danko.


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