Sandpoint
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sandpoint clear sky chart from 2005-11-05 to 2018-03-11.

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
48%
15738
12%
49171
11%
15708
49%
15708
19%
34491

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
25%
818
5%
2756
4%
816
27%
816
7%
2330
January16th to endNight
32%
832
6%
2912
6%
832
33%
832
9%
2339
February1st to 15thNight
33%
764
6%
2620
5%
760
35%
760
11%
2076
February16th to endNight
39%
684
12%
2051
12%
684
41%
684
15%
1566
March1st to 15thNight
39%
764
6%
2292
5%
764
40%
764
14%
1778
March16th to endNight
38%
768
7%
2028
4%
768
40%
768
15%
1637
April1st to 15thNight
50%
710
10%
1790
6%
710
51%
710
22%
1321
April16th to endNight
51%
540
15%
1620
12%
540
52%
540
23%
1080
May1st to 15thNight
62%
406
15%
1486
20%
406
63%
406
27%
842
May16th to endNight
58%
374
12%
1409
17%
374
60%
374
21%
875
June1st to 15thNight
59%
360
7%
1260
8%
360
59%
360
23%
781
June16th to endNight
65%
360
11%
1260
10%
360
66%
360
31%
717
July1st to 15thNight
83%
340
16%
1259
18%
340
86%
340
53%
510
July16th to endNight
86%
376
25%
1416
42%
354
87%
354
59%
505
August1st to 15thNight
85%
382
29%
1454
38%
380
88%
380
55%
561
August16th to endNight
80%
633
32%
1779
26%
633
81%
633
57%
870
September1st to 15thNight
79%
720
28%
1824
17%
720
80%
720
57%
965
September16th to endNight
65%
716
22%
1980
19%
716
67%
716
35%
1217
October1st to 15thNight
57%
720
16%
2100
15%
720
59%
720
26%
1371
October16th to endNight
49%
768
15%
2496
15%
768
52%
768
20%
1718
November1st to 15thNight
33%
760
7%
2470
7%
760
34%
760
10%
2008
November16th to endNight
34%
928
4%
2864
3%
928
35%
928
11%
2317
December1st to 15thNight
34%
975
6%
2925
5%
975
35%
975
10%
2407
December16th to endNight
23%
1040
4%
3120
2%
1040
25%
1040
7%
2700

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%35%5%24445%37%
49478
Night
18%10%35%424446%35%
49337
Cloud CoverDay
16%9%35%5%24446%37%
49479
Night
18%11%35%423346%35%
49340
TransparencyDay
48%5%13%19%10%2
49146
Night
50%5%13%17%10%2
49172
SeeingDay
18%9%22%27%17%3
6277
Night
24%412%32%22%2
15742

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
31%19%46%42433315%
1523
16th to endDay
25%22%47%424235%17%
1664
February1st to 15thDay
25%19%5%7%42334320%
1572
16th to endDay
20%18%5%9%7%32335%21%
1709
March1st to 15thDay
27%17%46%5%2333419%
1904
16th to endDay
27%14%47%7%35%44416%
2192
April1st to 15thDay
20%12%47%7%35%5%5%6%22%
2158
16th to endDay
16%9%47%7%36%5%5%5%28%
2340
May1st to 15thDay
11%7%25%5%35%45%7%40%
2463
16th to endDay
16%7%26%5%36%5%6%8%32%
2702
June1st to 15thDay
20%6%35%5%35%447%32%
2700
16th to endDay
13%425%5%45%5%5%6%42%
2700
July1st to 15thDay
4113423346%64%
2622
16th to endDay
11312346%73%
2657
August1st to 15thDay
42211235%8%66%
2497
16th to endDay
421331445%6%63%
2422
September1st to 15thDay
5%213324346%62%
2136
16th to endDay
13%5%2443345%7%47%
1980
October1st to 15thDay
18%6%35%5%24335%40%
1859
16th to endDay
28%5%35%5%2434432%
1728
November1st to 15thDay
32%14%35%424345%19%
1719
16th to endDay
28%17%5%7%6%2233318%
1410
December1st to 15thDay
25%14%6%9%6%23335%17%
1365
16th to endDay
29%22%5%7%5%3322413%
1456
January1st to 15thNight
33%16%5%7%42233317%
2756
16th to endNight
25%18%5%6%423335%21%
2912
February1st to 15thNight
26%17%45%31334326%
2609
16th to endNight
18%16%46%423336%28%
2051
March1st to 15thNight
23%11%36%5%34446%24%
2292
16th to endNight
23%10%36%7%35%5%5%5%23%
2025
April1st to 15thNight
14%8%36%6%36%5%5%8%31%
1790
16th to endNight
14%7%36%5%34446%38%
1620
May1st to 15thNight
10%5%335%345%6%9%43%
1486
16th to endNight
13%6%25%5%345%6%8%37%
1409
June1st to 15thNight
12%6%24435%5%5%8%39%
1260
16th to endNight
11%324425%5%5%7%46%
1260
July1st to 15thNight
2112213337%70%
1335
16th to endNight
111213245%75%
1512
August1st to 15thNight
321112248%70%
1462
16th to endNight
222213345%69%
1779
September1st to 15thNight
422213446%66%
1824
16th to endNight
11%4235%3435%6%49%
1980
October1st to 15thNight
16%5%24424445%43%
2100
16th to endNight
21%5%35%5%23446%37%
2496
November1st to 15thNight
28%12%36%5%3335%5%21%
2470
16th to endNight
29%15%34324345%22%
2864
December1st to 15thNight
22%17%5%6%5%24335%20%
2925
16th to endNight
28%22%5%6%42232416%
3120

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
30%21%5%7%42323315%
1523
16th to endDay
25%21%46%5%2334417%
1664
February1st to 15thDay
23%19%6%7%42333419%
1572
16th to endDay
20%18%6%7%7%3334420%
1709
March1st to 15thDay
27%17%46%5%2423419%
1904
16th to endDay
27%14%47%6%45%43417%
2193
April1st to 15thDay
19%12%37%7%35%5%5%6%22%
2158
16th to endDay
15%10%47%6%45%5%5%5%28%
2340
May1st to 15thDay
11%7%36%5%3446%7%41%
2463
16th to endDay
15%7%35%5%35%5%6%8%33%
2702
June1st to 15thDay
20%7%35%5%35%45%6%32%
2700
16th to endDay
13%425%5%45%5%5%6%42%
2700
July1st to 15thDay
4112423346%64%
2622
16th to endDay
11212346%73%
2657
August1st to 15thDay
412223348%66%
2497
16th to endDay
4213324446%63%
2422
September1st to 15thDay
4213324447%62%
2136
16th to endDay
13%5%24433347%47%
1980
October1st to 15thDay
18%7%245%23345%40%
1859
16th to endDay
26%6%25%5%23345%32%
1728
November1st to 15thDay
31%15%35%5%23335%18%
1719
16th to endDay
26%19%46%6%2234319%
1410
December1st to 15thDay
24%16%7%9%5%14336%17%
1365
16th to endDay
27%24%5%7%5%2422413%
1456
January1st to 15thNight
32%19%47%41223417%
2756
16th to endNight
24%19%5%7%423435%21%
2912
February1st to 15thNight
25%18%45%32333425%
2609
16th to endNight
17%17%47%433345%28%
2051
March1st to 15thNight
23%12%46%5%2445%7%23%
2292
16th to endNight
23%10%46%5%35%45%6%23%
2028
April1st to 15thNight
14%8%37%6%345%6%7%31%
1790
16th to endNight
13%8%25%5%25%45%6%39%
1620
May1st to 15thNight
10%5%25%4335%6%9%43%
1486
16th to endNight
12%7%25%44346%8%37%
1409
June1st to 15thNight
13%6%25%426%5%6%7%39%
1260
16th to endNight
11%3234246%5%7%47%
1260
July1st to 15thNight
212223346%70%
1335
16th to endNight
1111212226%75%
1512
August1st to 15thNight
2311112348%70%
1462
16th to endNight
22222344470%
1779
September1st to 15thNight
42112135%5%6%65%
1824
16th to endNight
11%5%235%2435%7%49%
1980
October1st to 15thNight
16%5%24434446%43%
2100
16th to endNight
21%7%26%423446%36%
2496
November1st to 15thNight
28%13%47%434345%20%
2470
16th to endNight
29%15%34323345%21%
2864
December1st to 15thNight
21%19%6%7%424345%20%
2925
16th to endNight
27%24%5%6%42323416%
3120

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
73%6%10%6%1
1523
16th to endDay
69%7%10%8%3
1664
February1st to 15thDay
68%6%11%9%3
1572
16th to endDay
67%410%12%3
1709
March1st to 15thDay
68%6%13%10%1
1904
16th to endDay
70%413%9%1
2193
April1st to 15thDay
60%6%15%14%3
2158
16th to endDay
54%7%15%17%3
2340
May1st to 15thDay
40%5%17%25%10%
2463
16th to endDay
47%7%21%19%4
2706
June1st to 15thDay
50%5%11%20%9%1
2700
16th to endDay
40%5%14%27%12%1
2700
July1st to 15thDay
21%310%30%24%8%
2469
16th to endDay
11%310%27%35%10%
2490
August1st to 15thDay
16%411%35%26%6%
2480
16th to endDay
20%5%13%30%26%4
2422
September1st to 15thDay
21%413%30%24%5%
2136
16th to endDay
37%6%18%23%10%2
1980
October1st to 15thDay
46%414%25%8%
1859
16th to endDay
55%5%16%18%4
1728
November1st to 15thDay
68%7%10%9%21
1719
16th to endDay
70%5%13%8%2
1410
December1st to 15thDay
70%5%10%10%1
1365
16th to endDay
77%48%6%2
1456
January1st to 15thNight
73%5%10%8%2
2756
16th to endNight
65%6%15%8%11
2912
February1st to 15thNight
63%7%13%11%3
2620
16th to endNight
58%5%12%17%5%
2051
March1st to 15thNight
59%6%17%13%2
2292
16th to endNight
60%7%14%12%4
2028
April1st to 15thNight
49%6%16%19%6%
1790
16th to endNight
45%415%25%7%
1620
May1st to 15thNight
35%5%15%28%14%
1487
16th to endNight
42%5%18%22%9%
1409
June1st to 15thNight
41%6%11%25%12%3
1260
16th to endNight
33%5%13%26%17%3
1260
July1st to 15thNight
14%47%26%31%14%
1259
16th to endNight
11%27%22%36%20%
1416
August1st to 15thNight
14%28%28%35%11%
1454
16th to endNight
16%39%28%33%7%
1779
September1st to 15thNight
17%5%9%30%27%9%
1824
16th to endNight
34%416%22%15%5%
1980
October1st to 15thNight
42%5%14%26%10%1
2100
16th to endNight
48%6%14%22%7%
2496
November1st to 15thNight
65%7%11%10%31
2470
16th to endNight
63%7%15%9%2
2864
December1st to 15thNight
67%6%12%11%1
2925
16th to endNight
73%5%10%7%1
3120

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
33%47%30%18%5%
90
16th to endDay
47%5%19%15%11%
96
February1st to 15thDay
30%9%23%26%8%1
123
16th to endDay
31%13%18%22%11%1
290
March1st to 15thDay
35%17%22%17%5%1
312
16th to endDay
33%14%22%24%4
288
April1st to 15thDay
22%16%27%21%9%2
269
16th to endDay
20%15%27%19%13%3
270
May1st to 15thDay
13%14%29%26%15%
288
16th to endDay
16%6%20%28%21%6%
417
June1st to 15thDay
17%9%22%27%20%4
495
16th to endDay
12%8%23%29%22%4
495
July1st to 15thDay
4421%33%29%5%
403
16th to endDay
17%29%38%17%5%
327
August1st to 15thDay
45%22%30%29%7%
315
16th to endDay
37%25%31%25%7%
332
September1st to 15thDay
6%8%24%28%25%6%
315
16th to endDay
13%8%21%29%20%5%
315
October1st to 15thDay
25%8%21%29%15%
279
16th to endDay
36%6%13%28%12%2
144
November1st to 15thDay
39%7%13%28%11%
135
16th to endDay
38%5%17%24%11%2
93
December1st to 15thDay
36%6%14%25%11%5%
90
16th to endDay
38%423%28%5%
96
January1st to 15thNight
41%6%12%25%11%2
820
16th to endNight
35%5%13%32%12%
832
February1st to 15thNight
37%414%29%11%1
764
16th to endNight
28%5%15%32%16%
684
March1st to 15thNight
29%7%14%31%15%1
764
16th to endNight
27%6%15%36%13%1
768
April1st to 15thNight
17%6%16%34%23%2
710
16th to endNight
17%5%17%36%19%2
540
May1st to 15thNight
13%413%38%25%5%
407
16th to endNight
16%312%25%37%4
375
June1st to 15thNight
14%314%35%27%4
360
16th to endNight
12%111%37%33%4
360
July1st to 15thNight
316%37%46%5%
340
16th to endNight
216%38%48%2
376
August1st to 15thNight
416%28%52%6%
382
16th to endNight
319%35%43%7%
633
September1st to 15thNight
5%110%32%41%8%
720
16th to endNight
13%29%33%34%5%
716
October1st to 15thNight
20%310%36%27%1
720
16th to endNight
25%413%32%22%1
768
November1st to 15thNight
36%7%13%33%9%
760
16th to endNight
38%6%12%26%15%
928
December1st to 15thNight
33%5%14%32%13%
975
16th to endNight
42%6%15%30%5%
1040
Page generated at 2018-03-12 10:28:09. Version ac04

Copyright 2018 A. Danko


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