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 2025-05-26.

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	12% 10% 3 7% 4 4 4 3 5% 6% 41%	117372
	Night	14% 11% 3 7% 5% 4 4 4 5% 6% 37%	120633
Transparency	Day	43% 6% 12% 21% 13% 5%	117140
	Night	47% 7% 12% 19% 11% 4	120511
Seeing	Day	18% 12% 24% 25% 16% 5%	15519
	Night	21% 7% 17% 32% 21% 3	24813

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	22% 27% 9% 11% 5% 4 3 2 4 4 9%	3639
	11th to 20th	Day	16% 11% 4 9% 6% 6% 5% 4 5% 7% 28%	3616
	21st to end	Day	19% 15% 4 7% 5% 4 4 3 6% 6% 27%	4004
February	1st to 10th	Day	22% 19% 5% 8% 5% 4 4 4 5% 5% 21%	1600
	11th to 20th	Day	18% 19% 5% 8% 4 4 4 3 4 6% 24%	1872
	21st to end	Day	18% 21% 5% 9% 6% 4 4 3 4 4 22%	1650
March	1st to 10th	Day	10% 13% 3 7% 6% 5% 6% 5% 7% 8% 31%	4518
	11th to 20th	Day	12% 11% 3 7% 5% 5% 5% 4 5% 6% 37%	4733
	21st to end	Day	17% 15% 4 10% 6% 6% 6% 4 5% 6% 20%	5850
April	1st to 10th	Day	16% 15% 3 8% 5% 6% 5% 5% 7% 7% 24%	2400
	11th to 20th	Day	13% 10% 4 8% 7% 5% 5% 4 5% 6% 34%	2465
	21st to end	Day	14% 10% 2 9% 6% 5% 4 4 6% 7% 34%	2600
May	1st to 10th	Day	11% 7% 3 8% 5% 5% 5% 4 6% 7% 38%	4420
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 6% 11% 44%	4517
	21st to end	Day	12% 7% 3 7% 6% 6% 6% 5% 6% 8% 34%	5004
June	1st to 10th	Day	17% 8% 2 7% 5% 5% 4 4 4 7% 38%	2850
	11th to 20th	Day	16% 6% 2 6% 5% 5% 5% 4 7% 8% 37%	2850
	21st to end	Day	7% 3 1 4 4 4 5% 4 6% 7% 55%	2850
July	1st to 10th	Day	2 2 1 2 2 2 3 2 4 4 76%	4552
	11th to 20th	Day	2 1 1 2 2 1 2 2 3 4 80%	4420
	21st to end	Day	1 1 2 2 3 3 3 5% 5% 75%	4790
August	1st to 10th	Day	4 2 1 3 3 2 3 2 4 6% 70%	4401
	11th to 20th	Day	4 3 1 3 2 3 3 3 6% 7% 66%	4099
	21st to end	Day	3 3 1 3 2 4 4 3 6% 7% 64%	4314
September	1st to 10th	Day	6% 3 1 4 2 3 3 3 6% 6% 65%	2280
	11th to 20th	Day	9% 4 2 6% 4 4 5% 3 5% 7% 49%	2152
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 6% 8% 47%	2090
October	1st to 10th	Day	10% 4 2 4 3 3 3 3 4 7% 57%	3411
	11th to 20th	Day	12% 7% 3 6% 4 5% 5% 3 6% 7% 43%	2922
	21st to end	Day	19% 11% 3 8% 4 4 6% 4 5% 5% 30%	3101
November	1st to 10th	Day	28% 14% 3 6% 5% 4 3 3 4 6% 23%	1764
	11th to 20th	Day	24% 16% 4 9% 5% 4 4 3 4 4 23%	1734
	21st to end	Day	20% 19% 6% 10% 5% 5% 4 4 4 4 21%	1410
December	1st to 10th	Day	15% 13% 7% 10% 6% 4 5% 4 6% 7% 24%	2290
	11th to 20th	Day	20% 25% 6% 12% 6% 5% 4 4 3 4 10%	2642
	21st to end	Day	20% 24% 7% 11% 5% 5% 5% 3 3 4 12%	3562
January	1st to 10th	Night	24% 22% 5% 10% 6% 5% 5% 3 3 4 11%	6306
	11th to 20th	Night	14% 11% 3 8% 6% 4 6% 5% 7% 7% 28%	6282
	21st to end	Night	21% 14% 3 6% 4 4 4 4 9% 6% 26%	6952
February	1st to 10th	Night	21% 19% 4 7% 4 4 3 3 5% 5% 24%	2800
	11th to 20th	Night	17% 16% 5% 8% 5% 4 3 3 4 6% 28%	2411
	21st to end	Night	14% 16% 4 9% 5% 5% 4 4 5% 6% 29%	1980
March	1st to 10th	Night	9% 11% 3 8% 4 4 5% 4 5% 7% 40%	5376
	11th to 20th	Night	12% 12% 4 8% 4 4 4 3 4 5% 41%	5265
	21st to end	Night	15% 11% 3 9% 6% 6% 6% 5% 7% 8% 23%	5121
April	1st to 10th	Night	11% 11% 3 7% 5% 5% 6% 4 7% 9% 33%	2000
	11th to 20th	Night	13% 10% 2 7% 6% 5% 4 3 5% 5% 41%	1886
	21st to end	Night	12% 9% 3 7% 5% 4 6% 4 6% 6% 39%	1800
May	1st to 10th	Night	12% 8% 3 6% 6% 6% 6% 4 6% 8% 37%	2762
	11th to 20th	Night	8% 6% 3 6% 4 4 4 4 6% 9% 46%	2596
	21st to end	Night	15% 6% 3 7% 6% 6% 5% 5% 6% 7% 34%	2687
June	1st to 10th	Night	13% 6% 3 7% 5% 4 4 4 5% 7% 43%	1330
	11th to 20th	Night	12% 5% 2 7% 5% 5% 6% 4 6% 8% 42%	1330
	21st to end	Night	6% 4 2 5% 4 4 4 4 6% 7% 54%	1330
July	1st to 10th	Night	2 1 1 3 3 3 2 3 4 4 75%	2403
	11th to 20th	Night	2 1 1 2 2 1 2 2 3 3 82%	2540
	21st to end	Night	3 2 1 2 2 2 2 2 4 5% 76%	2762
August	1st to 10th	Night	3 2 1 3 1 2 2 2 5% 6% 71%	2529
	11th to 20th	Night	3 3 1 4 3 4 4 3 5% 6% 63%	2736
	21st to end	Night	3 3 1 3 3 4 4 4 5% 6% 64%	3358
September	1st to 10th	Night	5% 2 1 4 3 2 3 3 4 8% 66%	1900
	11th to 20th	Night	7% 5% 2 5% 5% 4 4 3 6% 8% 51%	2028
	21st to end	Night	12% 4 2 5% 4 4 3 3 5% 7% 53%	2090
October	1st to 10th	Night	8% 4 1 4 2 3 4 3 5% 7% 60%	3568
	11th to 20th	Night	12% 5% 2 5% 4 4 5% 3 5% 7% 49%	4007
	21st to end	Night	14% 7% 2 6% 4 4 6% 4 6% 7% 40%	4457
November	1st to 10th	Night	24% 12% 3 6% 3 4 4 4 6% 7% 26%	2535
	11th to 20th	Night	22% 15% 4 8% 5% 5% 5% 4 4 5% 24%	2665
	21st to end	Night	22% 14% 4 8% 5% 4 4 4 5% 6% 24%	2966
December	1st to 10th	Night	13% 10% 4 9% 6% 5% 7% 6% 8% 6% 27%	4890
	11th to 20th	Night	19% 21% 6% 12% 6% 5% 5% 4 5% 5% 13%	5550
	21st to end	Night	19% 20% 7% 12% 6% 6% 5% 4 4 4 13%	7435

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	79% 7% 8% 5% 1	3639
	11th to 20th	Day	55% 7% 16% 17% 4 2	3640
	21st to end	Day	57% 6% 15% 17% 4	4004
February	1st to 10th	Day	67% 7% 11% 9% 5% 1	1600
	11th to 20th	Day	62% 8% 12% 11% 7%	1882
	21st to end	Day	66% 6% 8% 14% 5%	1650
March	1st to 10th	Day	48% 7% 13% 19% 13%	4518
	11th to 20th	Day	48% 5% 15% 28% 3	4734
	21st to end	Day	64% 8% 11% 12% 4	5850
April	1st to 10th	Day	58% 7% 17% 14% 4	2400
	11th to 20th	Day	50% 7% 14% 18% 10% 1	2465
	21st to end	Day	50% 9% 13% 19% 8% 1	2600
May	1st to 10th	Day	43% 8% 12% 28% 8%	4420
	11th to 20th	Day	33% 7% 19% 33% 8% 1	4520
	21st to end	Day	45% 10% 18% 22% 4	5005
June	1st to 10th	Day	47% 7% 13% 21% 11%	2850
	11th to 20th	Day	44% 8% 15% 21% 10% 2	2850
	21st to end	Day	28% 6% 14% 30% 19% 3	2850
July	1st to 10th	Day	13% 3 7% 21% 34% 22%	4483
	11th to 20th	Day	11% 3 6% 13% 29% 38%	4345
	21st to end	Day	12% 3 7% 20% 37% 21%	4639
August	1st to 10th	Day	17% 3 6% 24% 38% 13%	4384
	11th to 20th	Day	18% 4 9% 40% 24% 4	4139
	21st to end	Day	19% 4 12% 35% 26% 3	4313
September	1st to 10th	Day	21% 5% 11% 30% 23% 10%	2280
	11th to 20th	Day	33% 6% 13% 23% 21% 4	2152
	21st to end	Day	36% 8% 18% 24% 11% 4	2090
October	1st to 10th	Day	29% 4 13% 37% 17%	3411
	11th to 20th	Day	41% 6% 18% 24% 11% 1	2922
	21st to end	Day	54% 7% 14% 18% 6%	3101
November	1st to 10th	Day	63% 7% 13% 13% 3	1764
	11th to 20th	Day	66% 8% 12% 9% 4 1	1734
	21st to end	Day	67% 6% 10% 12% 4	1410
December	1st to 10th	Day	61% 9% 17% 12% 2	2290
	11th to 20th	Day	78% 6% 8% 7% 1	2644
	21st to end	Day	75% 6% 9% 7% 3	3562
January	1st to 10th	Night	76% 7% 9% 7% 1	6306
	11th to 20th	Night	53% 9% 16% 13% 7% 1	6320
	21st to end	Night	56% 6% 14% 19% 4	6952
February	1st to 10th	Night	62% 7% 13% 12% 5% 1	2800
	11th to 20th	Night	58% 6% 15% 13% 7% 1	2412
	21st to end	Night	56% 8% 12% 17% 6% 1	1980
March	1st to 10th	Night	42% 6% 13% 24% 14% 1	5376
	11th to 20th	Night	47% 5% 13% 28% 8%	5265
	21st to end	Night	56% 11% 14% 17% 3	5121
April	1st to 10th	Night	46% 8% 15% 23% 7%	2000
	11th to 20th	Night	45% 5% 12% 23% 14% 1	1886
	21st to end	Night	43% 8% 12% 24% 12% 1	1800
May	1st to 10th	Night	42% 8% 13% 24% 12% 1	2762
	11th to 20th	Night	30% 8% 13% 32% 16% 1	2596
	21st to end	Night	44% 13% 14% 21% 9%	2687
June	1st to 10th	Night	41% 8% 9% 24% 17% 2	1330
	11th to 20th	Night	39% 7% 12% 24% 14% 4	1330
	21st to end	Night	28% 5% 12% 27% 22% 6%	1330
July	1st to 10th	Night	13% 2 6% 15% 35% 28%	2363
	11th to 20th	Night	9% 2 5% 12% 22% 51%	2492
	21st to end	Night	12% 2 4 16% 33% 33%	2674
August	1st to 10th	Night	15% 3 5% 19% 39% 19%	2521
	11th to 20th	Night	22% 4 7% 32% 28% 8%	2762
	21st to end	Night	21% 5% 10% 26% 30% 8%	3358
September	1st to 10th	Night	19% 4 9% 27% 28% 12%	1900
	11th to 20th	Night	31% 6% 10% 23% 23% 7%	2028
	21st to end	Night	31% 5% 16% 27% 16% 6%	2090
October	1st to 10th	Night	25% 4 11% 41% 18% 1	3568
	11th to 20th	Night	36% 4 15% 24% 19% 1	4007
	21st to end	Night	40% 8% 14% 28% 8% 2	4457
November	1st to 10th	Night	56% 8% 16% 15% 4 1	2535
	11th to 20th	Night	62% 8% 13% 11% 5% 2	2665
	21st to end	Night	61% 7% 14% 13% 5%	2966
December	1st to 10th	Night	56% 11% 17% 14% 2	4890
	11th to 20th	Night	74% 7% 12% 7% 1	5547
	21st to end	Night	72% 8% 10% 8% 2	7435

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	32% 17% 17% 20% 12% 3	200
	11th to 20th	Day	33% 14% 18% 18% 12% 6%	200
	21st to end	Day	31% 10% 25% 20% 11% 2	220
February	1st to 10th	Day	31% 17% 29% 14% 8% 2	200
	11th to 20th	Day	32% 14% 22% 21% 9% 1	442
	21st to end	Day	29% 18% 23% 20% 10% 1	414
March	1st to 10th	Day	25% 20% 24% 18% 10% 3	500
	11th to 20th	Day	23% 15% 22% 23% 15% 2	500
	21st to end	Day	27% 18% 25% 20% 9% 1	550
April	1st to 10th	Day	24% 15% 28% 21% 8% 4	500
	11th to 20th	Day	16% 22% 28% 19% 12% 3	492
	21st to end	Day	17% 15% 26% 24% 13% 3	500
May	1st to 10th	Day	13% 13% 26% 29% 14% 4	503
	11th to 20th	Day	18% 11% 28% 23% 15% 5%	528
	21st to end	Day	14% 9% 21% 29% 18% 8%	616
June	1st to 10th	Day	19% 9% 24% 24% 20% 5%	680
	11th to 20th	Day	18% 13% 30% 22% 14% 3	680
	21st to end	Day	7% 8% 24% 29% 26% 6%	680
July	1st to 10th	Day	5% 6% 23% 35% 26% 4	566
	11th to 20th	Day	4 9% 26% 35% 22% 5%	484
	21st to end	Day	3 8% 23% 35% 24% 7%	531
August	1st to 10th	Day	6% 6% 23% 34% 23% 8%	487
	11th to 20th	Day	4 3 21% 36% 25% 10%	477
	21st to end	Day	7% 9% 28% 25% 19% 11%	539
September	1st to 10th	Day	8% 9% 26% 27% 20% 10%	490
	11th to 20th	Day	12% 11% 25% 25% 21% 7%	490
	21st to end	Day	13% 12% 27% 22% 20% 5%	490
October	1st to 10th	Day	14% 9% 26% 26% 17% 7%	490
	11th to 20th	Day	20% 14% 21% 22% 14% 8%	354
	21st to end	Day	31% 11% 22% 22% 11% 2	330
November	1st to 10th	Day	36% 11% 17% 26% 10% 1	300
	11th to 20th	Day	36% 12% 20% 15% 15% 2	266
	21st to end	Day	27% 14% 21% 23% 14% 1	200
December	1st to 10th	Day	28% 14% 22% 15% 17% 5%	200
	11th to 20th	Day	36% 13% 24% 16% 10% 2	200
	21st to end	Day	38% 12% 19% 20% 9% 1	220
January	1st to 10th	Night	40% 9% 15% 24% 10% 2	800
	11th to 20th	Night	30% 8% 16% 30% 14% 2	800
	21st to end	Night	28% 6% 18% 31% 15% 2	880
February	1st to 10th	Night	33% 9% 21% 25% 11% 2	800
	11th to 20th	Night	28% 8% 17% 31% 14% 2	784
	21st to end	Night	23% 11% 20% 27% 17% 2	660
March	1st to 10th	Night	22% 9% 18% 31% 18% 1	800
	11th to 20th	Night	23% 10% 16% 32% 18% 1	800
	21st to end	Night	23% 8% 22% 33% 12% 2	880
April	1st to 10th	Night	18% 8% 19% 37% 18% 2	800
	11th to 20th	Night	17% 8% 24% 34% 16% 1	698
	21st to end	Night	16% 8% 21% 33% 21% 2	600
May	1st to 10th	Night	11% 6% 21% 33% 26% 3	490
	11th to 20th	Night	12% 5% 18% 30% 29% 7%	394
	21st to end	Night	15% 5% 15% 28% 31% 5%	422
June	1st to 10th	Night	15% 4 18% 35% 24% 4	380
	11th to 20th	Night	14% 7% 22% 33% 22% 2	380
	21st to end	Night	7% 3 12% 40% 33% 4	380
July	1st to 10th	Night	3 2 12% 40% 41% 2	370
	11th to 20th	Night	3 2 14% 46% 31% 3	368
	21st to end	Night	2 2 9% 42% 42% 3	416
August	1st to 10th	Night	3 3 9% 39% 39% 6%	378
	11th to 20th	Night	4 1 8% 38% 40% 9%	513
	21st to end	Night	5% 4 14% 35% 39% 3	748
September	1st to 10th	Night	6% 2 14% 38% 34% 7%	760
	11th to 20th	Night	9% 4 15% 30% 34% 8%	760
	21st to end	Night	13% 5% 17% 34% 26% 5%	760
October	1st to 10th	Night	16% 5% 13% 38% 26% 2	760
	11th to 20th	Night	19% 5% 16% 30% 26% 3	760
	21st to end	Night	22% 8% 19% 31% 17% 3	836
November	1st to 10th	Night	32% 7% 13% 34% 13%	780
	11th to 20th	Night	32% 10% 17% 27% 13% 1	800
	21st to end	Night	31% 8% 15% 28% 16% 2	966
December	1st to 10th	Night	26% 9% 16% 30% 18% 1	1000
	11th to 20th	Night	36% 7% 19% 29% 9%	1000
	21st to end	Night	37% 11% 18% 26% 9%	1090

Page generated at 2025-05-23 06:20:58. Version ac07

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