Penticton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Penticton clear sky chart from 2005-11-05 to 2017-04-24.

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
42%
14382
11%
45381
8%
14352
45%
14352
17%
32527

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
28%
720
6%
2506
5%
716
30%
716
8%
2044
January16th to endNight
33%
768
8%
2688
6%
768
36%
768
11%
2068
February1st to 15thNight
35%
700
7%
2375
6%
698
38%
698
11%
1829
February16th to endNight
39%
632
10%
1963
8%
632
42%
632
15%
1462
March1st to 15thNight
31%
720
7%
2160
5%
720
35%
720
12%
1705
March16th to endNight
35%
768
9%
2001
4%
768
38%
768
14%
1582
April1st to 15thNight
43%
719
9%
1799
4%
719
45%
719
19%
1365
April16th to endNight
43%
502
11%
1546
9%
502
46%
502
18%
1098
May1st to 15thNight
51%
329
14%
1319
18%
329
57%
329
21%
782
May16th to endNight
54%
342
6%
1368
9%
342
56%
342
16%
926
June1st to 15thNight
47%
330
5%
1131
2%
330
48%
330
18%
765
June16th to endNight
52%
330
7%
991
1%
330
53%
330
25%
655
July1st to 15thNight
65%
310
9%
1140
6%
310
68%
310
34%
585
July16th to endNight
70%
348
16%
1304
21%
326
76%
326
45%
544
August1st to 15thNight
75%
330
22%
1312
31%
328
77%
328
35%
618
August16th to endNight
64%
588
22%
1638
16%
588
67%
588
41%
920
September1st to 15thNight
65%
660
24%
1650
12%
660
69%
660
43%
970
September16th to endNight
58%
656
22%
1779
16%
656
61%
656
32%
1121
October1st to 15thNight
51%
660
14%
1980
13%
660
55%
660
23%
1324
October16th to endNight
41%
704
10%
2262
7%
704
46%
704
15%
1656
November1st to 15thNight
30%
700
9%
2383
8%
700
33%
700
11%
1869
November16th to endNight
25%
757
6%
2557
3%
757
29%
757
9%
2084
December1st to 15thNight
30%
900
7%
2700
5%
900
31%
900
10%
2187
December16th to endNight
24%
909
7%
2829
3%
909
28%
909
8%
2368

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
8%8%37%6%36%5%5%7%35%
46241
Night
8%10%47%6%35%5%5%7%34%
45544
Cloud CoverDay
9%9%47%6%46%5%5%7%33%
46241
Night
9%10%47%6%35%5%5%7%33%
45548
TransparencyDay
50%9%13%17%8%1
45907
Night
49%8%14%18%7%1
45382
SeeingDay
16%17%30%23%10%2
5361
Night
15%9%23%30%17%3
14388

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 15thDay
10%12%5%11%9%46%6%6%9%17%
1432
16th to endDay
7%14%7%10%8%35%6%6%6%23%
1536
February1st to 15thDay
6%12%6%11%9%46%6%46%24%
1487
16th to endDay
6%11%49%9%46%7%7%7%25%
1511
March1st to 15thDay
7%11%5%8%7%45%7%7%9%25%
1800
16th to endDay
6%12%5%9%9%5%7%5%6%8%23%
2220
April1st to 15thDay
9%11%46%8%5%7%6%5%7%26%
2149
16th to endDay
8%11%37%6%46%5%6%9%30%
2272
May1st to 15thDay
9%8%26%6%35%6%5%8%37%
2301
16th to endDay
12%8%37%7%36%6%5%8%29%
2391
June1st to 15thDay
17%7%36%6%35%45%6%32%
2494
16th to endDay
13%426%6%47%6%6%7%34%
2637
July1st to 15thDay
5%3245%35%45%6%52%
2412
16th to endDay
4313425%5%5%6%58%
2461
August1st to 15thDay
42125%35%46%9%54%
2310
16th to endDay
6%313436%46%8%52%
2211
September1st to 15thDay
5%413423445%59%
1980
16th to endDay
10%5%24425%5%5%8%45%
1849
October1st to 15thDay
8%7%25%6%45%5%5%5%41%
1650
16th to endDay
11%10%49%6%45%5%46%30%
1609
November1st to 15thDay
12%10%48%8%47%5%6%8%23%
1476
16th to endDay
8%12%8%10%7%47%5%6%5%22%
1389
December1st to 15thDay
6%14%5%12%9%38%6%6%6%20%
1260
16th to endDay
8%15%6%12%8%45%5%5%6%19%
1404
January1st to 15thNight
10%15%8%13%9%45%5%5%6%16%
2506
16th to endNight
7%16%6%11%9%46%5%6%6%19%
2688
February1st to 15thNight
9%13%5%9%8%45%5%5%6%25%
2363
16th to endNight
6%12%48%6%35%7%6%7%31%
1963
March1st to 15thNight
7%10%5%8%7%5%6%47%8%28%
2160
16th to endNight
7%8%48%8%46%5%6%8%30%
1997
April1st to 15thNight
8%7%37%5%45%5%6%10%35%
1799
16th to endNight
7%8%36%6%46%5%6%8%36%
1546
May1st to 15thNight
8%5%15%435%5%6%7%45%
1319
16th to endNight
11%6%35%445%6%6%10%35%
1368
June1st to 15thNight
12%6%35%5%25%6%5%8%37%
1131
16th to endNight
8%415%5%35%5%6%7%46%
991
July1st to 15thNight
322425%46%6%59%
1215
16th to endNight
31122345%7%67%
1400
August1st to 15thNight
421332345%7%62%
1320
16th to endNight
22133245%5%8%59%
1638
September1st to 15thNight
4213324446%62%
1650
16th to endNight
6%5%2342445%9%51%
1779
October1st to 15thNight
8%6%26%5%35%6%5%5%45%
1980
16th to endNight
12%9%47%6%35%6%6%7%31%
2262
November1st to 15thNight
11%12%5%8%7%35%5%6%7%27%
2383
16th to endNight
9%16%7%9%8%46%5%46%21%
2557
December1st to 15thNight
7%15%7%12%9%46%5%5%7%17%
2700
16th to endNight
9%17%6%11%8%5%6%5%5%6%15%
2829

Percentage Cloud Cover SW (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
12%12%6%10%7%5%8%5%5%7%17%
1432
16th to endDay
8%16%6%10%7%4447%6%23%
1536
February1st to 15thDay
9%14%7%10%8%36%5%46%22%
1487
16th to endDay
6%12%5%10%8%47%6%6%7%24%
1511
March1st to 15thDay
9%13%49%7%47%5%6%8%22%
1800
16th to endDay
8%14%5%11%8%46%6%6%7%19%
2220
April1st to 15thDay
9%12%5%9%8%5%6%6%6%7%22%
2149
16th to endDay
8%12%38%7%45%6%6%8%28%
2272
May1st to 15thDay
8%9%46%6%45%6%5%7%34%
2301
16th to endDay
13%8%48%7%5%7%6%5%6%26%
2391
June1st to 15thDay
16%8%46%7%3445%7%31%
2494
16th to endDay
12%6%36%7%46%6%7%8%30%
2637
July1st to 15thDay
5%425%5%25%45%7%51%
2412
16th to endDay
431343445%5%58%
2461
August1st to 15thDay
43135%25%5%6%9%53%
2310
16th to endDay
6%414435%46%8%50%
2211
September1st to 15thDay
6%424423346%57%
1980
16th to endDay
11%5%24435%46%8%42%
1849
October1st to 15thDay
9%8%36%5%5%5%5%5%6%38%
1650
16th to endDay
14%11%48%5%36%346%29%
1609
November1st to 15thDay
15%12%410%6%5%5%6%5%6%22%
1476
16th to endDay
9%15%8%10%6%36%6%6%5%20%
1389
December1st to 15thDay
8%13%6%11%7%47%8%5%7%19%
1260
16th to endDay
11%13%6%13%8%46%5%45%18%
1404
January1st to 15thNight
13%14%7%11%9%46%5%5%6%15%
2506
16th to endNight
10%15%6%9%7%46%5%6%6%21%
2688
February1st to 15thNight
11%14%5%8%7%36%5%5%6%24%
2363
16th to endNight
6%14%49%7%35%5%5%7%30%
1963
March1st to 15thNight
8%11%5%9%8%46%5%5%8%25%
2160
16th to endNight
7%10%310%7%5%6%5%6%7%27%
2001
April1st to 15thNight
8%8%38%6%36%6%7%9%32%
1799
16th to endNight
6%8%46%7%46%5%6%9%33%
1546
May1st to 15thNight
7%7%235%25%5%6%7%44%
1319
16th to endNight
11%7%25%6%47%6%6%9%32%
1368
June1st to 15thNight
11%7%35%5%36%6%5%7%36%
1131
16th to endNight
8%315%6%36%5%6%7%44%
991
July1st to 15thNight
33134235%6%7%57%
1215
16th to endNight
31131335%7%67%
1400
August1st to 15thNight
5%2133235%47%61%
1320
16th to endNight
33133235%6%8%56%
1638
September1st to 15thNight
421332445%6%60%
1650
16th to endNight
7%6%2433345%8%49%
1779
October1st to 15thNight
8%6%36%5%35%5%5%6%42%
1980
16th to endNight
14%10%36%6%35%5%6%7%29%
2262
November1st to 15thNight
16%11%5%7%7%35%46%6%24%
2383
16th to endNight
11%15%8%9%8%346%45%20%
2557
December1st to 15thNight
10%15%6%11%8%5%6%5%5%7%18%
2700
16th to endNight
12%18%6%10%7%45%6%6%6%16%
2829

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%9%12%9%3
1432
16th to endDay
58%8%13%14%31
1536
February1st to 15thDay
61%10%13%11%2
1487
16th to endDay
60%9%13%11%5%
1511
March1st to 15thDay
61%11%12%11%2
1800
16th to endDay
65%10%13%8%2
2220
April1st to 15thDay
62%10%12%11%2
2149
16th to endDay
54%11%13%16%4
2272
May1st to 15thDay
49%7%15%19%7%
2301
16th to endDay
59%9%13%14%3
2395
June1st to 15thDay
54%9%12%13%7%2
2494
16th to endDay
50%10%13%16%8%
2637
July1st to 15thDay
33%6%13%22%18%5%
2258
16th to endDay
28%7%13%25%20%5%
2294
August1st to 15thDay
27%8%15%31%13%2
2293
16th to endDay
30%8%14%27%16%2
2211
September1st to 15thDay
28%6%14%26%20%2
1980
16th to endDay
38%9%14%22%12%2
1849
October1st to 15thDay
46%8%14%22%7%
1650
16th to endDay
54%9%14%17%3
1609
November1st to 15thDay
61%11%10%11%31
1476
16th to endDay
61%10%11%12%4
1389
December1st to 15thDay
58%11%13%14%2
1260
16th to endDay
64%10%11%10%3
1404
January1st to 15thNight
66%7%12%9%3
2506
16th to endNight
58%8%14%12%41
2688
February1st to 15thNight
59%7%14%12%4
2375
16th to endNight
53%8%15%15%5%
1963
March1st to 15thNight
59%8%14%13%3
2160
16th to endNight
55%10%14%15%3
2001
April1st to 15thNight
48%11%16%18%5%
1799
16th to endNight
45%10%16%22%4
1546
May1st to 15thNight
36%9%17%23%13%
1320
16th to endNight
46%9%19%20%4
1368
June1st to 15thNight
45%8%12%22%9%1
1131
16th to endNight
37%11%16%23%10%
991
July1st to 15thNight
24%8%14%28%19%5%
1140
16th to endNight
17%415%30%26%4
1304
August1st to 15thNight
23%6%14%34%18%2
1312
16th to endNight
23%8%15%32%17%2
1638
September1st to 15thNight
24%7%14%29%20%4
1650
16th to endNight
32%9%12%27%15%3
1779
October1st to 15thNight
42%8%15%22%10%
1980
16th to endNight
52%8%15%19%4
2262
November1st to 15thNight
60%9%12%13%31
2383
16th to endNight
65%7%10%11%4
2557
December1st to 15thNight
62%8%12%14%1
2700
16th to endNight
64%11%10%10%2
2829

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
10%5%18%31%28%6%
60
16th to endDay
15%17%34%28%31
64
February1st to 15thDay
22%18%29%23%41
147
16th to endDay
17%20%32%19%8%1
227
March1st to 15thDay
20%35%28%11%3
270
16th to endDay
23%29%29%13%2
288
April1st to 15thDay
24%23%25%18%5%2
269
16th to endDay
18%23%32%14%8%2
243
May1st to 15thDay
17%18%35%20%6%2
228
16th to endDay
22%16%24%19%13%3
266
June1st to 15thDay
17%13%23%26%15%2
439
16th to endDay
14%10%31%27%14%1
582
July1st to 15thDay
9%13%30%31%13%1
342
16th to endDay
414%34%29%12%3
271
August1st to 15thDay
9%8%30%32%16%3
255
16th to endDay
12%12%33%30%7%2
268
September1st to 15thDay
9%16%30%25%13%3
255
16th to endDay
18%14%32%20%10%2
255
October1st to 15thDay
18%21%30%20%7%
255
16th to endDay
23%8%28%25%11%2
121
November1st to 15thDay
30%19%27%19%2
72
16th to endDay
18%10%28%18%13%11%
60
December1st to 15thDay
10%21%25%26%11%5%
60
16th to endDay
9%14%40%21%9%4
64
January1st to 15thNight
23%13%24%25%11%1
720
16th to endNight
16%10%27%30%12%1
768
February1st to 15thNight
20%10%21%32%13%1
704
16th to endNight
13%11%25%28%17%2
632
March1st to 15thNight
15%15%29%24%11%2
720
16th to endNight
14%14%27%30%11%2
768
April1st to 15thNight
12%10%25%31%17%3
719
16th to endNight
11%10%28%32%14%1
502
May1st to 15thNight
13%6%23%34%19%2
330
16th to endNight
13%5%21%27%28%4
343
June1st to 15thNight
14%8%23%28%24%
330
16th to endNight
9%423%39%21%2
330
July1st to 15thNight
6%5%18%33%33%3
310
16th to endNight
3419%38%30%3
348
August1st to 15thNight
6%111%30%44%5%
330
16th to endNight
7%317%36%29%4
588
September1st to 15thNight
6%7%16%28%29%12%
660
16th to endNight
10%5%19%32%25%5%
656
October1st to 15thNight
14%7%18%35%20%3
660
16th to endNight
21%9%20%30%14%3
704
November1st to 15thNight
23%14%26%26%7%1
700
16th to endNight
21%12%27%23%11%3
757
December1st to 15thNight
20%10%26%32%9%1
900
16th to endNight
24%11%29%28%6%
909
Page generated at 2017-04-25 04:48:17. Version ac04

Copyright 2017 A. Danko


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