Woodbridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Woodbridge clear sky chart from 2005-11-05 to 2017-12-20.

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
35%
15197
14%
47963
9%
15161
41%
15161
19%
33068

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%
718
9%
2470
3%
716
24%
716
9%
1942
January16th to endNight
19%
768
11%
2496
4%
768
28%
768
12%
1913
February1st to 15thNight
16%
701
10%
2287
2%
701
25%
701
11%
1748
February16th to endNight
22%
631
12%
2014
4%
631
32%
631
14%
1477
March1st to 15thNight
22%
720
13%
1980
6%
720
29%
720
16%
1458
March16th to endNight
31%
768
20%
2112
11%
768
39%
768
23%
1449
April1st to 15thNight
26%
718
14%
1822
5%
718
31%
718
22%
1318
April16th to endNight
36%
558
19%
1638
8%
558
45%
558
26%
1069
May1st to 15thNight
46%
495
17%
1575
12%
495
53%
495
25%
1023
May16th to endNight
48%
374
17%
1497
15%
374
57%
374
26%
836
June1st to 15thNight
45%
360
13%
1440
11%
360
54%
360
21%
839
June16th to endNight
55%
360
15%
1329
17%
360
62%
360
26%
772
July1st to 15thNight
63%
340
17%
1327
22%
340
69%
340
35%
675
July16th to endNight
62%
493
16%
1526
15%
462
65%
462
32%
867
August1st to 15thNight
68%
539
17%
1609
13%
536
70%
536
36%
945
August16th to endNight
62%
621
23%
1767
15%
621
66%
621
35%
1055
September1st to 15thNight
53%
720
21%
1815
10%
720
58%
720
35%
1161
September16th to endNight
56%
717
23%
2001
17%
717
60%
717
34%
1233
October1st to 15thNight
41%
720
17%
2160
14%
720
46%
720
23%
1457
October16th to endNight
25%
768
13%
2304
7%
768
33%
768
16%
1704
November1st to 15thNight
34%
760
17%
2579
14%
760
40%
760
19%
1752
November16th to endNight
26%
780
10%
2730
6%
780
32%
780
13%
2002
December1st to 15thNight
16%
780
6%
2730
3%
780
21%
780
10%
2128
December16th to endNight
13%
788
6%
2755
1%
788
18%
788
7%
2245

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%37%6%35%5%5%7%32%
48857
Night
15%8%36%5%3445%6%35%
48143
Cloud CoverDay
15%8%36%6%35%45%7%32%
48867
Night
15%8%36%5%3445%6%35%
48147
TransparencyDay
49%7%13%18%9%
48556
Night
47%6%13%20%10%1
47963
SeeingDay
17%8%27%25%14%6%
5749
Night
19%8%30%28%12%1
15203

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
18%12%5%9%7%46%5%45%21%
1465
16th to endDay
12%15%6%10%9%47%45%5%17%
1728
February1st to 15thDay
14%14%6%11%7%45%45%420%
1575
16th to endDay
17%13%47%6%24447%26%
1455
March1st to 15thDay
15%9%48%7%35%45%5%28%
1969
16th to endDay
15%8%47%6%3444434%
2112
April1st to 15thDay
20%9%36%5%3445%7%29%
2125
16th to endDay
18%6%35%5%2435%5%38%
2333
May1st to 15thDay
15%7%25%6%35%45%7%35%
2376
16th to endDay
11%6%25%5%35%5%5%7%40%
2618
June1st to 15thDay
14%6%25%5%345%5%9%37%
2520
16th to endDay
13%415%5%45%5%6%10%36%
2622
July1st to 15thDay
7%426%5%37%6%7%8%39%
2547
16th to endDay
9%427%6%35%6%8%10%34%
2535
August1st to 15thDay
7%5%27%6%45%6%7%8%37%
2340
16th to endDay
10%426%6%35%6%6%9%38%
2423
September1st to 15thDay
14%6%26%5%3445%7%40%
2143
16th to endDay
13%6%36%5%3445%8%39%
1959
October1st to 15thDay
19%7%36%5%2445%5%33%
1800
16th to endDay
24%10%47%6%45%5%46%22%
1920
November1st to 15thDay
14%10%38%5%15%5%5%8%31%
1604
16th to endDay
17%12%5%8%6%35%5%5%7%22%
1560
December1st to 15thDay
17%13%7%10%7%35%446%18%
1560
16th to endDay
21%13%6%9%6%3446%6%17%
1568
January1st to 15thNight
20%13%5%8%6%345%5%5%21%
2470
16th to endNight
13%12%6%9%7%46%346%23%
2496
February1st to 15thNight
13%14%5%7%7%35%45%5%25%
2285
16th to endNight
13%11%49%8%25%5%46%28%
2014
March1st to 15thNight
17%9%46%7%34445%31%
1968
16th to endNight
14%8%46%424335%43%
2112
April1st to 15thNight
18%7%35%5%3445%6%34%
1822
16th to endNight
12%7%345%24447%43%
1638
May1st to 15thNight
15%5%245%25%6%48%40%
1575
16th to endNight
12%42342346%6%49%
1495
June1st to 15thNight
12%5%345%3445%9%41%
1440
16th to endNight
9%5%244345%5%8%45%
1329
July1st to 15thNight
6%313314448%57%
1407
16th to endNight
7%215%426%5%5%8%48%
1631
August1st to 15thNight
6%41443446%9%50%
1620
16th to endNight
8%414434446%53%
1767
September1st to 15thNight
11%4144345%5%6%48%
1815
16th to endNight
11%5%2442345%8%47%
2001
October1st to 15thNight
18%6%26%5%24446%39%
2160
16th to endNight
19%8%36%5%346%5%7%29%
2304
November1st to 15thNight
17%8%25%5%3445%6%35%
2579
16th to endNight
19%9%37%6%35%45%7%26%
2730
December1st to 15thNight
19%13%48%6%35%46%6%21%
2730
16th to endNight
21%13%6%10%6%35%446%17%
2755

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
18%12%5%8%7%46%446%21%
1465
16th to endDay
13%14%6%10%10%46%5%5%5%17%
1728
February1st to 15thDay
15%13%7%10%7%45%445%20%
1575
16th to endDay
18%12%5%6%6%3445%6%26%
1455
March1st to 15thDay
16%9%5%8%6%34446%28%
1980
16th to endDay
16%9%37%5%3445%5%35%
2111
April1st to 15thDay
20%9%36%6%2445%6%30%
2125
16th to endDay
18%6%35%5%24346%38%
2333
May1st to 15thDay
16%6%25%6%3446%7%35%
2376
16th to endDay
12%6%25%5%35%5%5%7%41%
2618
June1st to 15thDay
15%5%25%5%3446%9%37%
2520
16th to endDay
13%425%5%45%5%6%10%36%
2622
July1st to 15thDay
8%425%5%37%6%7%8%40%
2547
16th to endDay
9%426%6%45%5%7%10%35%
2535
August1st to 15thDay
8%5%26%5%35%6%7%9%38%
2340
16th to endDay
10%5%17%5%35%5%6%9%39%
2423
September1st to 15thDay
15%5%25%5%3435%6%41%
2143
16th to endDay
13%5%36%5%3345%8%39%
1959
October1st to 15thDay
20%6%26%6%245%5%5%33%
1800
16th to endDay
24%10%37%5%445%5%6%23%
1920
November1st to 15thDay
15%9%47%5%2445%7%31%
1604
16th to endDay
18%13%5%7%6%25%5%5%7%23%
1560
December1st to 15thDay
17%14%5%10%7%45%45%6%18%
1560
16th to endDay
21%14%6%8%6%345%6%6%17%
1568
January1st to 15thNight
20%14%5%8%6%345%5%5%21%
2470
16th to endNight
14%13%6%8%7%45%446%24%
2496
February1st to 15thNight
13%14%6%7%7%35%45%5%26%
2278
16th to endNight
14%11%48%7%35%5%45%29%
2014
March1st to 15thNight
18%8%46%6%34445%31%
1980
16th to endNight
15%8%36%424335%42%
2112
April1st to 15thNight
18%7%26%5%25%446%34%
1822
16th to endNight
12%7%35%5%24446%43%
1638
May1st to 15thNight
15%5%245%35%5%5%7%40%
1574
16th to endNight
12%5%2332446%6%49%
1495
June1st to 15thNight
12%5%335%345%49%41%
1440
16th to endNight
10%5%245%25%5%5%8%44%
1329
July1st to 15thNight
6%313325%5%48%56%
1407
16th to endNight
7%315%425%5%5%7%49%
1631
August1st to 15thNight
6%41443446%8%50%
1620
16th to endNight
9%31443445%6%53%
1767
September1st to 15thNight
11%4244235%6%6%48%
1815
16th to endNight
11%425%423447%48%
2001
October1st to 15thNight
18%5%25%5%2435%6%39%
2160
16th to endNight
20%8%27%5%345%5%6%29%
2304
November1st to 15thNight
17%7%35%5%3445%6%35%
2579
16th to endNight
20%10%46%6%3445%7%26%
2730
December1st to 15thNight
20%13%48%6%3446%5%21%
2730
16th to endNight
21%13%6%10%7%34446%17%
2755

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
64%6%12%12%5%
1466
16th to endDay
66%7%10%10%4
1728
February1st to 15thDay
64%7%11%12%3
1577
16th to endDay
56%6%14%13%6%1
1455
March1st to 15thDay
56%6%12%15%8%
1980
16th to endDay
50%5%11%18%13%1
2112
April1st to 15thDay
53%5%11%18%10%
2125
16th to endDay
47%5%10%20%14%2
2333
May1st to 15thDay
46%6%12%21%12%
2376
16th to endDay
40%8%14%21%13%1
2622
June1st to 15thDay
42%6%14%23%12%
2520
16th to endDay
40%8%16%21%12%
2622
July1st to 15thDay
36%8%15%23%15%2
2398
16th to endDay
41%9%15%21%10%1
2378
August1st to 15thDay
38%9%17%18%13%1
2327
16th to endDay
38%7%15%26%10%
2423
September1st to 15thDay
41%7%15%23%10%
2143
16th to endDay
40%7%13%28%9%
1959
October1st to 15thDay
50%6%12%20%9%1
1800
16th to endDay
59%8%14%12%4
1920
November1st to 15thDay
49%7%16%18%7%
1604
16th to endDay
58%7%16%12%4
1560
December1st to 15thDay
64%8%13%10%2
1560
16th to endDay
65%9%12%9%2
1568
January1st to 15thNight
63%6%11%11%5%
2470
16th to endNight
60%6%13%15%4
2496
February1st to 15thNight
58%7%10%17%5%
2287
16th to endNight
55%5%14%16%7%
2014
March1st to 15thNight
53%6%12%19%6%
1980
16th to endNight
45%5%8%22%16%2
2112
April1st to 15thNight
49%5%11%18%14%
1822
16th to endNight
40%6%11%20%17%3
1638
May1st to 15thNight
41%6%12%22%15%2
1575
16th to endNight
35%5%14%26%15%3
1497
June1st to 15thNight
37%7%13%23%16%1
1440
16th to endNight
35%6%12%26%17%
1329
July1st to 15thNight
25%6%12%26%25%2
1327
16th to endNight
31%6%15%26%16%3
1526
August1st to 15thNight
29%8%18%28%13%1
1609
16th to endNight
31%7%11%31%16%1
1767
September1st to 15thNight
33%7%15%27%15%1
1815
16th to endNight
34%6%12%32%13%
2001
October1st to 15thNight
45%5%12%23%13%
2160
16th to endNight
53%7%14%17%7%
2304
November1st to 15thNight
47%6%14%19%10%1
2579
16th to endNight
55%7%17%14%4
2730
December1st to 15thNight
61%7%14%12%3
2730
16th to endNight
67%7%13%9%2
2755

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
16%24%38%9%9%1
65
16th to endDay
37%18%23%19%
96
February1st to 15thDay
21%27%37%12%1
90
16th to endDay
21%14%43%17%2
87
March1st to 15thDay
22%13%32%22%8%
270
16th to endDay
22%10%32%23%8%2
288
April1st to 15thDay
22%14%30%23%7%1
270
16th to endDay
19%10%31%21%12%4
270
May1st to 15thDay
21%6%26%23%12%9%
288
16th to endDay
15%5%30%26%16%5%
331
June1st to 15thDay
17%8%21%33%16%2
315
16th to endDay
15%5%28%32%14%3
417
July1st to 15thDay
10%222%35%18%10%
332
16th to endDay
8%224%36%18%9%
326
August1st to 15thDay
10%120%30%23%13%
313
16th to endDay
12%418%25%20%18%
332
September1st to 15thDay
14%219%25%22%15%
315
16th to endDay
14%419%23%22%15%
314
October1st to 15thDay
20%6%29%20%15%6%
315
16th to endDay
25%11%31%23%8%
336
November1st to 15thDay
18%14%27%27%9%2
127
16th to endDay
18%15%40%21%4
90
December1st to 15thDay
18%20%40%16%4
90
16th to endDay
30%22%40%6%
72
January1st to 15thNight
27%16%34%17%4
720
16th to endNight
20%9%38%25%5%
768
February1st to 15thNight
20%13%39%21%4
704
16th to endNight
20%12%36%26%4
631
March1st to 15thNight
22%12%36%24%4
720
16th to endNight
19%10%34%25%10%
768
April1st to 15thNight
21%8%38%25%5%
718
16th to endNight
14%9%34%30%10%1
558
May1st to 15thNight
16%426%34%15%2
495
16th to endNight
12%429%34%18%
375
June1st to 15thNight
15%5%28%35%15%
360
16th to endNight
10%224%45%17%
360
July1st to 15thNight
6%121%46%22%1
340
16th to endNight
8%219%45%21%2
493
August1st to 15thNight
7%14%46%27%2
539
16th to endNight
9%218%34%30%3
621
September1st to 15thNight
13%423%28%24%5%
720
16th to endNight
13%319%29%28%5%
717
October1st to 15thNight
20%5%26%27%16%2
720
16th to endNight
25%10%32%26%5%
768
November1st to 15thNight
21%8%30%26%11%1
760
16th to endNight
24%12%30%25%7%1
780
December1st to 15thNight
28%12%37%17%3
780
16th to endNight
28%12%37%19%2
788
Page generated at 2017-12-21 07:04:44. Version ac04

Copyright 2017 A. Danko


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