Coeur d'Alene
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coeur d'Alene 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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	15% 10% 3 6% 5% 3 4 4 5% 6% 38%	78182
	Night	17% 11% 3 6% 5% 3 4 4 5% 6% 35%	81329
Transparency	Day	47% 7% 12% 19% 12% 3	77910
	Night	50% 7% 12% 17% 11% 3	81181
Seeing	Day	18% 12% 24% 25% 16% 4	13915
	Night	22% 7% 17% 31% 21% 3	23291

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	25% 26% 7% 7% 6% 3 4 3 4 4 11%	2539
	11th to 20th	Day	24% 14% 4 7% 7% 4 5% 5% 5% 6% 20%	2516
	21st to end	Day	28% 18% 5% 7% 6% 3 4 4 4 4 15%	2794
February	1st to 10th	Day	23% 17% 5% 6% 6% 3 4 5% 5% 5% 20%	1520
	11th to 20th	Day	19% 18% 5% 7% 5% 3 4 4 4 6% 25%	1775
	21st to end	Day	19% 19% 6% 8% 7% 3 4 4 4 4 22%	1570
March	1st to 10th	Day	20% 15% 5% 7% 7% 3 6% 3 4 6% 25%	1871
	11th to 20th	Day	20% 13% 4 7% 6% 4 6% 5% 5% 5% 25%	1869
	21st to end	Day	21% 16% 5% 9% 7% 4 5% 4 4 5% 20%	2322
April	1st to 10th	Day	17% 14% 4 7% 6% 5% 5% 6% 6% 7% 23%	2160
	11th to 20th	Day	14% 10% 4 8% 8% 4 5% 5% 5% 6% 32%	2215
	21st to end	Day	14% 9% 3 7% 6% 3 6% 5% 6% 7% 34%	2340
May	1st to 10th	Day	10% 6% 3 6% 6% 3 5% 5% 6% 8% 42%	2436
	11th to 20th	Day	13% 5% 3 6% 7% 3 5% 5% 6% 9% 37%	2477
	21st to end	Day	15% 7% 3 6% 6% 3 5% 5% 6% 8% 35%	2785
June	1st to 10th	Day	18% 7% 3 5% 5% 3 5% 4 4 7% 38%	2700
	11th to 20th	Day	16% 6% 2 6% 6% 3 5% 4 7% 8% 36%	2700
	21st to end	Day	7% 3 2 3 5% 3 4 5% 5% 7% 55%	2700
July	1st to 10th	Day	4 2 1 3 3 2 4 3 5% 6% 66%	2596
	11th to 20th	Day	4 2 1 3 3 1 3 3 4 6% 70%	2520
	21st to end	Day	1 1 2 2 1 2 3 3 5% 79%	2741
August	1st to 10th	Day	4 2 1 2 3 2 3 3 4 6% 70%	2507
	11th to 20th	Day	5% 2 1 2 3 2 3 3 5% 6% 68%	2346
	21st to end	Day	5% 4 1 3 4 3 5% 4 6% 7% 59%	2458
September	1st to 10th	Day	6% 3 1 3 3 2 3 3 6% 6% 64%	2160
	11th to 20th	Day	9% 4 2 6% 5% 3 5% 4 5% 7% 50%	2039
	21st to end	Day	10% 6% 2 5% 5% 3 5% 5% 6% 8% 46%	1980
October	1st to 10th	Day	15% 7% 3 6% 5% 2 4 3 4 6% 45%	1940
	11th to 20th	Day	17% 8% 3 4 5% 2 4 3 5% 5% 44%	1672
	21st to end	Day	22% 9% 3 5% 5% 3 5% 4 5% 5% 35%	1782
November	1st to 10th	Day	29% 14% 4 5% 5% 4 3 4 4 6% 23%	1674
	11th to 20th	Day	25% 15% 5% 7% 6% 3 4 4 3 4 23%	1648
	21st to end	Day	21% 18% 6% 8% 6% 3 5% 4 4 4 22%	1340
December	1st to 10th	Day	21% 15% 7% 9% 6% 3 4 4 5% 5% 20%	1330
	11th to 20th	Day	25% 22% 7% 10% 6% 3 4 5% 3 4 11%	1682
	21st to end	Day	20% 20% 5% 10% 6% 4 5% 4 4 5% 17%	2478
January	1st to 10th	Night	27% 22% 5% 7% 6% 4 4 4 3 4 14%	4406
	11th to 20th	Night	21% 14% 4 8% 6% 3 4 4 5% 7% 24%	4382
	21st to end	Night	30% 17% 5% 7% 5% 3 4 3 3 5% 18%	4862
February	1st to 10th	Night	22% 18% 5% 6% 4 3 3 4 5% 5% 25%	2660
	11th to 20th	Night	17% 15% 4 7% 6% 3 4 4 4 6% 29%	2288
	21st to end	Night	15% 15% 4 8% 6% 4 5% 4 5% 7% 28%	1884
March	1st to 10th	Night	17% 12% 4 7% 7% 3 5% 5% 5% 6% 29%	2249
	11th to 20th	Night	18% 11% 3 6% 6% 3 5% 5% 5% 7% 31%	2089
	21st to end	Night	18% 11% 3 7% 7% 4 6% 6% 7% 6% 25%	2030
April	1st to 10th	Night	12% 10% 4 6% 5% 4 6% 6% 7% 9% 33%	1800
	11th to 20th	Night	14% 10% 3 7% 6% 3 5% 4 4 5% 39%	1696
	21st to end	Night	12% 8% 4 6% 5% 3 6% 5% 6% 6% 39%	1620
May	1st to 10th	Night	9% 6% 3 4 6% 3 6% 6% 6% 8% 44%	1522
	11th to 20th	Night	10% 7% 3 6% 5% 3 5% 5% 6% 9% 43%	1416
	21st to end	Night	13% 6% 3 6% 7% 4 5% 5% 5% 9% 39%	1490
June	1st to 10th	Night	13% 6% 3 6% 6% 3 5% 5% 5% 7% 43%	1260
	11th to 20th	Night	12% 5% 2 6% 5% 3 6% 5% 5% 7% 42%	1260
	21st to end	Night	6% 3 2 5% 4 4 4 5% 5% 7% 54%	1260
July	1st to 10th	Night	2 1 1 3 3 2 4 3 4 5% 72%	1359
	11th to 20th	Night	3 1 1 3 2 1 3 3 4 5% 73%	1440
	21st to end	Night	2 1 1 2 2 2 3 3 4 5% 77%	1576
August	1st to 10th	Night	3 3 2 2 1 3 3 5% 7% 71%	1432
	11th to 20th	Night	3 2 1 2 4 2 3 3 4 5% 71%	1553
	21st to end	Night	4 3 1 3 3 2 3 4 5% 7% 64%	1896
September	1st to 10th	Night	5% 2 2 3 4 2 3 3 4 8% 65%	1800
	11th to 20th	Night	7% 5% 2 4 6% 3 4 4 5% 7% 53%	1921
	21st to end	Night	12% 4 2 4 4 3 3 3 5% 7% 52%	1980
October	1st to 10th	Night	13% 6% 1 5% 4 3 4 4 5% 7% 47%	2019
	11th to 20th	Night	15% 6% 3 5% 6% 3 4 4 4 7% 44%	2287
	21st to end	Night	19% 7% 3 5% 5% 3 4 4 5% 6% 40%	2574
November	1st to 10th	Night	25% 12% 3 5% 4 3 4 5% 6% 7% 26%	2405
	11th to 20th	Night	23% 13% 4 7% 6% 3 5% 6% 4 5% 24%	2531
	21st to end	Night	23% 12% 4 7% 6% 3 5% 5% 5% 6% 26%	2817
December	1st to 10th	Night	20% 13% 5% 8% 6% 2 5% 4 5% 6% 25%	2850
	11th to 20th	Night	24% 18% 6% 9% 7% 3 5% 4 4 5% 14%	3510
	21st to end	Night	21% 16% 5% 8% 8% 4 6% 6% 5% 5% 16%	5205

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	77% 7% 10% 5% 2	2539
	11th to 20th	Day	64% 6% 12% 13% 3 2	2540
	21st to end	Day	73% 6% 12% 7% 1 1	2794
February	1st to 10th	Day	67% 7% 12% 9% 4 1	1520
	11th to 20th	Day	62% 9% 12% 11% 7%	1785
	21st to end	Day	67% 6% 8% 14% 5%	1570
March	1st to 10th	Day	61% 7% 12% 12% 6% 1	1871
	11th to 20th	Day	61% 8% 12% 17% 3	1870
	21st to end	Day	67% 7% 14% 9% 2	2322
April	1st to 10th	Day	59% 7% 17% 14% 4	2160
	11th to 20th	Day	53% 7% 14% 17% 9% 1	2215
	21st to end	Day	51% 9% 13% 19% 7% 1	2340
May	1st to 10th	Day	39% 9% 15% 26% 10%	2436
	11th to 20th	Day	43% 8% 16% 24% 8%	2480
	21st to end	Day	45% 8% 17% 23% 6% 1	2786
June	1st to 10th	Day	47% 7% 14% 22% 10%	2700
	11th to 20th	Day	45% 8% 15% 21% 8% 2	2700
	21st to end	Day	28% 7% 14% 30% 19% 3	2700
July	1st to 10th	Day	20% 4 10% 29% 25% 12%	2527
	11th to 20th	Day	16% 5% 11% 22% 34% 12%	2445
	21st to end	Day	10% 4 6% 22% 44% 14%	2589
August	1st to 10th	Day	17% 4 8% 26% 33% 13%	2490
	11th to 20th	Day	17% 5% 10% 28% 33% 6%	2346
	21st to end	Day	24% 6% 11% 28% 26% 5%	2458
September	1st to 10th	Day	21% 5% 11% 30% 23% 9%	2160
	11th to 20th	Day	32% 6% 12% 23% 23% 4	2039
	21st to end	Day	36% 8% 19% 22% 11% 4	1980
October	1st to 10th	Day	42% 5% 13% 30% 11%	1940
	11th to 20th	Day	44% 6% 15% 26% 8% 1	1672
	21st to end	Day	52% 7% 15% 19% 7%	1782
November	1st to 10th	Day	64% 7% 13% 12% 3	1674
	11th to 20th	Day	66% 8% 12% 9% 4 1	1648
	21st to end	Day	66% 6% 10% 13% 4	1340
December	1st to 10th	Day	66% 8% 10% 12% 3	1330
	11th to 20th	Day	78% 6% 8% 7% 1	1684
	21st to end	Day	69% 6% 12% 9% 4	2478
January	1st to 10th	Night	73% 8% 9% 8% 1 1	4406
	11th to 20th	Night	59% 7% 12% 15% 5% 2	4420
	21st to end	Night	70% 7% 12% 9% 2 1	4862
February	1st to 10th	Night	62% 7% 14% 12% 4 1	2660
	11th to 20th	Night	58% 6% 16% 13% 7%	2289
	21st to end	Night	57% 8% 11% 17% 6% 1	1884
March	1st to 10th	Night	56% 7% 13% 16% 7% 1	2249
	11th to 20th	Night	53% 8% 12% 19% 8%	2089
	21st to end	Night	57% 10% 13% 15% 5%	2030
April	1st to 10th	Night	46% 9% 14% 24% 7% 1	1800
	11th to 20th	Night	48% 5% 12% 21% 13% 1	1696
	21st to end	Night	44% 8% 12% 24% 11% 1	1620
May	1st to 10th	Night	35% 9% 15% 28% 12% 1	1522
	11th to 20th	Night	37% 7% 14% 28% 14% 1	1416
	21st to end	Night	41% 8% 16% 25% 10%	1490
June	1st to 10th	Night	41% 8% 9% 24% 16% 2	1260
	11th to 20th	Night	40% 7% 12% 24% 13% 4	1260
	21st to end	Night	28% 6% 12% 27% 21% 6%	1260
July	1st to 10th	Night	15% 3 8% 23% 33% 18%	1319
	11th to 20th	Night	14% 3 8% 21% 32% 22%	1392
	21st to end	Night	11% 2 5% 15% 40% 27%	1488
August	1st to 10th	Night	15% 4 7% 17% 38% 19%	1424
	11th to 20th	Night	16% 4 8% 23% 36% 13%	1553
	21st to end	Night	19% 6% 8% 24% 32% 11%	1896
September	1st to 10th	Night	20% 5% 9% 27% 28% 12%	1800
	11th to 20th	Night	30% 6% 9% 23% 24% 7%	1921
	21st to end	Night	32% 5% 16% 26% 16% 6%	1980
October	1st to 10th	Night	37% 5% 10% 33% 14% 1	2019
	11th to 20th	Night	43% 5% 13% 24% 14% 1	2287
	21st to end	Night	44% 9% 13% 22% 11% 1	2574
November	1st to 10th	Night	57% 8% 15% 15% 4 1	2405
	11th to 20th	Night	61% 8% 13% 11% 5% 2	2531
	21st to end	Night	59% 7% 15% 14% 5%	2817
December	1st to 10th	Night	61% 8% 12% 15% 3	2850
	11th to 20th	Night	72% 7% 11% 9% 1	3507
	21st to end	Night	66% 10% 12% 9% 3	5205

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 19% 17% 19% 12% 3	180
	11th to 20th	Day	36% 14% 18% 16% 10% 6%	180
	21st to end	Day	34% 12% 26% 17% 11%	198
February	1st to 10th	Day	33% 17% 30% 11% 8% 1	180
	11th to 20th	Day	33% 15% 23% 20% 8% 1	405
	21st to end	Day	29% 18% 24% 19% 9% 1	382
March	1st to 10th	Day	27% 22% 22% 17% 10% 2	449
	11th to 20th	Day	24% 15% 21% 23% 16% 1	420
	21st to end	Day	28% 18% 25% 19% 8% 1	462
April	1st to 10th	Day	25% 14% 30% 21% 7% 3	420
	11th to 20th	Day	18% 23% 27% 17% 10% 4	412
	21st to end	Day	19% 16% 26% 25% 12% 2	420
May	1st to 10th	Day	13% 14% 27% 30% 13% 3	423
	11th to 20th	Day	19% 10% 26% 23% 17% 6%	448
	21st to end	Day	15% 9% 20% 29% 19% 8%	547
June	1st to 10th	Day	19% 9% 23% 24% 20% 5%	630
	11th to 20th	Day	18% 14% 29% 22% 14% 3	630
	21st to end	Day	7% 8% 24% 30% 25% 6%	630
July	1st to 10th	Day	6% 6% 24% 35% 25% 3	522
	11th to 20th	Day	4 10% 28% 35% 19% 4	444
	21st to end	Day	3 8% 24% 35% 23% 7%	487
August	1st to 10th	Day	6% 6% 24% 33% 24% 8%	447
	11th to 20th	Day	4 3 21% 37% 24% 10%	437
	21st to end	Day	7% 9% 29% 26% 20% 9%	495
September	1st to 10th	Day	9% 9% 27% 28% 20% 7%	450
	11th to 20th	Day	11% 12% 24% 24% 21% 7%	450
	21st to end	Day	14% 13% 27% 22% 20% 4	450
October	1st to 10th	Day	16% 9% 27% 26% 16% 6%	450
	11th to 20th	Day	20% 14% 22% 22% 13% 8%	322
	21st to end	Day	31% 12% 23% 21% 10% 3	297
November	1st to 10th	Day	37% 12% 16% 26% 9%	270
	11th to 20th	Day	36% 11% 19% 17% 16% 1	240
	21st to end	Day	27% 13% 21% 22% 15% 1	180
December	1st to 10th	Day	29% 14% 22% 16% 14% 4	180
	11th to 20th	Day	39% 13% 24% 16% 6% 2	180
	21st to end	Day	38% 12% 19% 20% 10% 1	198
January	1st to 10th	Night	40% 9% 16% 23% 10% 2	760
	11th to 20th	Night	31% 8% 16% 28% 13% 2	760
	21st to end	Night	29% 6% 18% 30% 14% 2	836
February	1st to 10th	Night	33% 8% 21% 25% 10% 2	760
	11th to 20th	Night	28% 8% 18% 30% 14% 2	744
	21st to end	Night	23% 11% 20% 27% 17% 2	628
March	1st to 10th	Night	23% 9% 19% 31% 17% 1	750
	11th to 20th	Night	24% 10% 16% 31% 18% 1	720
	21st to end	Night	23% 8% 21% 33% 13% 2	792
April	1st to 10th	Night	17% 7% 19% 37% 18% 2	720
	11th to 20th	Night	18% 8% 24% 32% 16% 2	628
	21st to end	Night	16% 8% 21% 32% 21% 2	540
May	1st to 10th	Night	12% 5% 22% 32% 26% 3	442
	11th to 20th	Night	10% 5% 17% 30% 30% 7%	354
	21st to end	Night	15% 5% 15% 28% 31% 6%	389
June	1st to 10th	Night	15% 4 18% 35% 24% 4	360
	11th to 20th	Night	15% 7% 22% 32% 22% 3	360
	21st to end	Night	7% 3 12% 39% 34% 4	360
July	1st to 10th	Night	3 2 11% 40% 42% 2	350
	11th to 20th	Night	3 3 15% 45% 31% 2	348
	21st to end	Night	2 1 9% 42% 42% 4	394
August	1st to 10th	Night	3 3 9% 38% 40% 7%	358
	11th to 20th	Night	4 1 7% 37% 41% 9%	485
	21st to end	Night	5% 4 13% 35% 39% 3	708
September	1st to 10th	Night	7% 3 14% 39% 33% 5%	720
	11th to 20th	Night	9% 4 15% 29% 35% 8%	720
	21st to end	Night	14% 5% 17% 33% 26% 5%	720
October	1st to 10th	Night	16% 5% 13% 38% 27% 2	720
	11th to 20th	Night	20% 6% 15% 31% 26% 3	720
	21st to end	Night	22% 7% 19% 30% 17% 4	792
November	1st to 10th	Night	32% 7% 14% 34% 12%	740
	11th to 20th	Night	33% 9% 17% 27% 14% 1	760
	21st to end	Night	31% 8% 15% 27% 16% 2	917
December	1st to 10th	Night	27% 9% 17% 30% 16% 1	950
	11th to 20th	Night	37% 7% 18% 28% 9%	950
	21st to end	Night	37% 10% 18% 26% 9%	1036

Page generated at 2024-03-05 04:24:00. Version ac07

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