Burwash
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burwash clear sky chart from 2005-11-05 to 2017-10-06.

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%
15229
13%
46965
8%
15193
36%
15193
18%
33290

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
17%
898
8%
2680
3%
895
21%
895
11%
2134
January16th to endNight
23%
856
13%
2584
6%
856
30%
856
13%
1986
February1st to 15thNight
19%
701
10%
2287
3%
701
26%
701
11%
1725
February16th to endNight
23%
631
11%
2003
5%
631
30%
631
12%
1531
March1st to 15thNight
21%
720
12%
2022
5%
720
28%
720
16%
1477
March16th to endNight
30%
768
20%
2112
9%
768
38%
768
24%
1411
April1st to 15thNight
26%
656
15%
1779
6%
656
31%
656
20%
1281
April16th to endNight
31%
540
17%
1620
8%
540
38%
540
21%
1104
May1st to 15thNight
35%
477
14%
1557
11%
477
42%
477
20%
1052
May16th to endNight
36%
375
12%
1466
9%
374
47%
374
20%
904
June1st to 15thNight
36%
360
10%
1260
8%
360
42%
360
20%
813
June16th to endNight
43%
360
11%
1260
9%
360
48%
360
23%
796
July1st to 15thNight
52%
340
15%
1190
14%
340
57%
340
31%
666
July16th to endNight
50%
461
14%
1396
12%
432
53%
432
27%
852
August1st to 15thNight
50%
539
15%
1609
11%
536
55%
536
28%
1028
August16th to endNight
51%
573
19%
1719
12%
573
57%
573
29%
1080
September1st to 15thNight
44%
712
17%
1843
9%
712
48%
712
32%
1197
September16th to endNight
45%
717
22%
1980
14%
717
50%
717
31%
1272
October1st to 15thNight
31%
684
16%
2046
11%
684
38%
684
20%
1427
October16th to endNight
22%
704
13%
2167
7%
704
29%
704
14%
1635
November1st to 15thNight
28%
700
14%
2408
10%
700
36%
700
15%
1673
November16th to endNight
24%
720
10%
2520
7%
720
29%
720
10%
1903
December1st to 15thNight
18%
777
8%
2577
2%
777
25%
777
10%
2020
December16th to endNight
19%
960
9%
2880
4%
960
24%
960
9%
2323

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
17%9%36%5%3445%6%32%
48237
Night
17%9%46%5%34446%32%
47128
Cloud CoverDay
17%9%36%5%3445%6%32%
48247
Night
17%9%46%5%34446%32%
47132
TransparencyDay
51%5%12%20%9%
47918
Night
51%5%12%20%9%1
46965
SeeingDay
21%12%30%21%9%4
5943
Night
22%10%28%27%10%1
15234

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%18%7%7%433345%23%
1256
16th to endDay
16%18%6%8%6%34445%21%
1638
February1st to 15thDay
12%15%5%8%8%345%45%24%
1575
16th to endDay
14%19%6%8%6%24335%25%
1467
March1st to 15thDay
16%10%47%5%35%346%32%
1926
16th to endDay
13%9%45%5%34345%40%
2112
April1st to 15thDay
21%10%25%42445%5%31%
2178
16th to endDay
22%7%24423235%39%
2340
May1st to 15thDay
20%7%35%5%2445%6%33%
2394
16th to endDay
16%5%245%345%5%6%38%
2648
June1st to 15thDay
17%7%37%6%345%6%7%31%
2700
16th to endDay
15%7%36%5%36%5%6%7%32%
2700
July1st to 15thDay
11%5%26%5%35%5%5%8%40%
2700
16th to endDay
12%5%25%6%35%6%6%8%36%
2670
August1st to 15thDay
16%6%26%5%345%5%8%36%
2340
16th to endDay
16%6%25%5%335%6%7%36%
2478
September1st to 15thDay
15%5%36%6%24447%38%
2106
16th to endDay
19%6%25%5%34346%38%
1980
October1st to 15thDay
20%7%35%5%35%447%32%
1711
16th to endDay
28%12%46%6%35%34421%
1702
November1st to 15thDay
19%12%27%5%2325%6%30%
1450
16th to endDay
25%17%47%6%2443320%
1440
December1st to 15thDay
19%18%49%6%33445%19%
1382
16th to endDay
21%18%6%9%5%2444416%
1344
January1st to 15thNight
20%15%5%9%6%25%44421%
2680
16th to endNight
15%13%7%9%7%35%445%23%
2584
February1st to 15thNight
12%13%6%10%7%35%5%46%24%
2285
16th to endNight
15%15%5%8%6%45%445%24%
2003
March1st to 15thNight
17%11%37%6%33446%30%
2010
16th to endNight
13%8%26%5%33346%41%
2112
April1st to 15thNight
20%10%445%23445%34%
1779
16th to endNight
19%7%36%5%24345%36%
1620
May1st to 15thNight
16%7%36%5%25%5%5%6%35%
1557
16th to endNight
12%5%35%6%25%45%7%40%
1464
June1st to 15thNight
15%7%35%5%345%6%6%37%
1260
16th to endNight
13%5%35%425%5%5%10%38%
1260
July1st to 15thNight
8%3245%245%6%9%46%
1260
16th to endNight
9%425%4246%6%8%44%
1494
August1st to 15thNight
12%5%35%5%34446%44%
1620
16th to endNight
12%6%2443345%6%46%
1719
September1st to 15thNight
13%414434446%46%
1843
16th to endNight
14%5%15%423348%45%
1980
October1st to 15thNight
21%8%25%5%23346%35%
2046
16th to endNight
27%8%37%6%23345%27%
2167
November1st to 15thNight
18%9%36%5%35%45%6%31%
2408
16th to endNight
24%11%46%5%345%45%24%
2520
December1st to 15thNight
21%14%48%6%34445%22%
2577
16th to endNight
22%15%5%8%6%34445%19%
2880

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%17%7%7%423345%24%
1256
16th to endDay
16%18%6%8%6%35%435%21%
1638
February1st to 15thDay
12%15%5%8%8%445%45%24%
1575
16th to endDay
14%19%6%7%6%24335%25%
1467
March1st to 15thDay
16%10%47%5%35%346%32%
1937
16th to endDay
13%9%45%5%24345%40%
2111
April1st to 15thDay
21%10%35%425%35%5%31%
2178
16th to endDay
21%7%24423236%39%
2340
May1st to 15thDay
20%7%35%5%2445%6%33%
2394
16th to endDay
16%5%245%345%5%6%38%
2648
June1st to 15thDay
17%7%37%6%345%6%7%31%
2700
16th to endDay
15%6%36%5%36%5%6%7%33%
2700
July1st to 15thDay
12%5%25%5%35%5%5%8%40%
2700
16th to endDay
12%5%25%5%36%5%6%8%36%
2670
August1st to 15thDay
16%6%26%435%5%5%7%36%
2340
16th to endDay
16%6%25%5%345%5%7%36%
2478
September1st to 15thDay
15%6%36%6%24447%38%
2106
16th to endDay
18%6%35%5%24346%38%
1980
October1st to 15thDay
20%8%35%5%35%447%32%
1711
16th to endDay
28%11%46%6%3434421%
1702
November1st to 15thDay
19%12%27%5%2335%6%30%
1450
16th to endDay
25%16%48%6%2343321%
1440
December1st to 15thDay
19%18%5%9%6%3444420%
1382
16th to endDay
21%18%7%9%5%25%44417%
1344
January1st to 15thNight
20%15%5%9%6%3444420%
2680
16th to endNight
15%13%7%9%7%25%445%23%
2584
February1st to 15thNight
12%13%6%9%7%35%5%46%24%
2278
16th to endNight
15%14%5%8%6%45%44424%
2003
March1st to 15thNight
17%11%37%6%33347%30%
2022
16th to endNight
13%8%26%5%33336%41%
2112
April1st to 15thNight
20%10%44424445%34%
1779
16th to endNight
19%7%35%5%25%345%37%
1620
May1st to 15thNight
16%7%36%5%35%5%5%6%35%
1556
16th to endNight
12%6%26%5%35%45%8%40%
1464
June1st to 15thNight
15%6%35%5%345%6%6%37%
1260
16th to endNight
13%435%425%5%5%10%38%
1260
July1st to 15thNight
8%4245%345%5%9%46%
1260
16th to endNight
9%425%4346%6%8%44%
1494
August1st to 15thNight
12%5%35%5%3445%5%44%
1620
16th to endNight
13%42443345%6%45%
1719
September1st to 15thNight
13%5%14424446%46%
1843
16th to endNight
14%5%25%423347%45%
1980
October1st to 15thNight
21%8%25%5%23346%35%
2046
16th to endNight
26%8%26%6%23345%27%
2167
November1st to 15thNight
18%9%35%5%3445%6%32%
2408
16th to endNight
24%11%46%5%34445%24%
2520
December1st to 15thNight
21%14%48%6%35%445%22%
2577
16th to endNight
22%15%5%8%6%3434419%
2880

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
63%313%15%5%
1257
16th to endDay
63%47%16%7%
1638
February1st to 15thDay
60%413%15%5%
1577
16th to endDay
62%29%16%8%
1467
March1st to 15thDay
52%413%18%10%
1937
16th to endDay
46%29%24%12%3
2112
April1st to 15thDay
53%410%19%10%1
2178
16th to endDay
47%28%23%14%2
2340
May1st to 15thDay
49%411%20%11%2
2394
16th to endDay
42%5%14%21%14%1
2652
June1st to 15thDay
49%5%11%21%12%
2700
16th to endDay
47%6%13%21%9%1
2700
July1st to 15thDay
38%6%13%27%13%
2541
16th to endDay
42%7%14%24%10%
2505
August1st to 15thDay
43%6%17%21%10%
2327
16th to endDay
44%6%16%27%5%
2478
September1st to 15thDay
44%6%14%24%8%
2106
16th to endDay
46%5%16%25%6%
1980
October1st to 15thDay
49%5%13%20%9%
1711
16th to endDay
65%5%13%9%5%
1702
November1st to 15thDay
53%5%13%19%7%
1450
16th to endDay
68%39%14%4
1440
December1st to 15thDay
67%49%14%4
1382
16th to endDay
69%39%12%3
1344
January1st to 15thNight
64%5%10%13%5%
2680
16th to endNight
62%39%18%7%
2584
February1st to 15thNight
59%5%13%15%5%
2287
16th to endNight
61%411%14%7%
2003
March1st to 15thNight
54%412%18%8%1
2022
16th to endNight
44%311%19%17%3
2112
April1st to 15thNight
52%38%20%13%1
1779
16th to endNight
49%29%19%16%2
1620
May1st to 15thNight
48%410%22%11%2
1557
16th to endNight
41%7%12%21%15%2
1466
June1st to 15thNight
43%6%12%23%11%2
1260
16th to endNight
40%7%14%22%14%1
1260
July1st to 15thNight
31%6%15%29%16%1
1190
16th to endNight
36%7%17%24%14%
1396
August1st to 15thNight
38%6%18%24%10%1
1609
16th to endNight
37%5%17%27%10%1
1719
September1st to 15thNight
36%6%16%28%9%1
1843
16th to endNight
38%413%33%8%
1980
October1st to 15thNight
49%412%21%11%
2046
16th to endNight
58%411%17%6%
2167
November1st to 15thNight
51%5%14%20%7%
2408
16th to endNight
60%5%13%15%4
2520
December1st to 15thNight
64%5%12%14%3
2577
16th to endNight
67%49%13%5%
2880

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
21%16%42%11%8%
61
16th to endDay
34%7%27%16%13%1
96
February1st to 15thDay
31%12%38%17%
90
16th to endDay
35%20%27%14%1
81
March1st to 15thDay
21%18%29%21%7%
227
16th to endDay
22%16%30%19%9%2
288
April1st to 15thDay
26%12%30%19%9%1
270
16th to endDay
28%14%27%14%10%4
270
May1st to 15thDay
27%9%27%18%12%5%
288
16th to endDay
21%16%31%19%9%2
361
June1st to 15thDay
21%17%32%21%5%
495
16th to endDay
18%14%36%21%8%1
495
July1st to 15thDay
12%12%35%25%10%3
475
16th to endDay
13%10%33%25%12%5%
428
August1st to 15thDay
19%322%28%15%9%
313
16th to endDay
19%6%25%19%15%11%
332
September1st to 15thDay
16%6%26%23%15%10%
315
16th to endDay
20%9%28%23%11%7%
314
October1st to 15thDay
17%12%32%24%10%2
278
16th to endDay
28%15%28%20%32
214
November1st to 15thDay
22%10%42%17%5%1
68
16th to endDay
35%15%26%20%3
60
December1st to 15thDay
33%13%36%15%1
60
16th to endDay
35%25%34%31
64
January1st to 15thNight
26%14%30%21%6%
900
16th to endNight
22%11%29%26%7%1
856
February1st to 15thNight
20%14%34%24%5%
704
16th to endNight
23%14%30%25%6%
631
March1st to 15thNight
23%16%30%24%4
720
16th to endNight
19%11%31%25%10%1
768
April1st to 15thNight
24%15%30%23%5%
656
16th to endNight
23%10%28%26%9%1
540
May1st to 15thNight
20%7%27%31%11%1
477
16th to endNight
13%9%35%30%10%
375
June1st to 15thNight
18%8%29%33%8%
360
16th to endNight
15%6%26%36%13%
360
July1st to 15thNight
10%427%46%9%1
340
16th to endNight
11%326%39%18%1
461
August1st to 15thNight
14%323%33%21%3
539
16th to endNight
15%5%21%32%24%1
573
September1st to 15thNight
16%6%28%25%20%2
712
16th to endNight
16%6%25%28%18%3
717
October1st to 15thNight
26%7%29%24%11%1
684
16th to endNight
30%11%26%25%4
704
November1st to 15thNight
24%12%29%25%8%
700
16th to endNight
30%12%25%23%7%
720
December1st to 15thNight
30%13%29%21%4
777
16th to endNight
30%14%24%23%6%
960
Page generated at 2017-10-07 14:07:43. Version ac04

Copyright 2017 A. Danko


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