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 2026-09-29.

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	10% 9% 3 6% 4 4 4 3 5% 6% 45%	153169
	Night	12% 10% 3 7% 4 4 5% 4 5% 6% 40%	146981
Transparency	Day	39% 6% 12% 23% 15% 5%	152896
	Night	44% 6% 12% 20% 13% 5%	146836
Seeing	Day	17% 11% 24% 25% 17% 5%	17349
	Night	21% 7% 17% 32% 21% 3	26411

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	20% 26% 8% 11% 5% 5% 4 3 4 4 10%	4723
	11th to 20th	Day	13% 9% 3 9% 6% 6% 5% 4 6% 7% 32%	4716
	21st to end	Day	16% 14% 4 8% 6% 4 5% 3 6% 6% 27%	5186
February	1st to 10th	Day	22% 19% 5% 8% 5% 4 4 4 5% 5% 20%	1680
	11th to 20th	Day	17% 19% 5% 9% 5% 4 4 4 4 6% 23%	1969
	21st to end	Day	18% 21% 5% 8% 6% 4 4 3 4 4 23%	1730
March	1st to 10th	Day	10% 13% 3 7% 5% 5% 6% 5% 7% 8% 31%	4618
	11th to 20th	Day	12% 12% 3 7% 5% 5% 5% 4 5% 6% 36%	4837
	21st to end	Day	17% 15% 4 10% 6% 6% 6% 4 5% 6% 21%	5979
April	1st to 10th	Day	15% 14% 3 7% 5% 6% 5% 4 7% 7% 25%	2520
	11th to 20th	Day	13% 10% 4 8% 7% 5% 5% 4 5% 6% 33%	2590
	21st to end	Day	13% 9% 2 8% 6% 5% 5% 4 6% 7% 35%	2730
May	1st to 10th	Day	7% 5% 2 6% 4 4 4 3 6% 8% 50%	7942
	11th to 20th	Day	9% 7% 2 7% 5% 4 5% 5% 7% 11% 38%	8160
	21st to end	Day	8% 6% 2 7% 5% 5% 5% 4 7% 9% 42%	9209
June	1st to 10th	Day	16% 8% 2 7% 5% 4 4 4 5% 7% 40%	3150
	11th to 20th	Day	14% 6% 2 6% 4 5% 5% 4 7% 8% 40%	3150
	21st to end	Day	7% 4 1 4 4 4 5% 4 6% 7% 54%	3150
July	1st to 10th	Day	3 2 1 3 2 3 3 2 4 5% 72%	8464
	11th to 20th	Day	3 2 1 3 2 2 3 2 3 4 74%	8220
	21st to end	Day	3 2 1 2 2 2 2 2 4 5% 76%	8916
August	1st to 10th	Day	3 2 1 2 2 2 2 2 3 5% 76%	6441
	11th to 20th	Day	3 2 1 3 2 3 3 3 6% 7% 66%	6038
	21st to end	Day	3 2 1 3 2 3 4 3 6% 7% 65%	6265
September	1st to 10th	Day	6% 3 1 4 2 3 3 3 6% 6% 63%	2520
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 3 5% 7% 50%	2378
	21st to end	Day	9% 5% 2 6% 4 4 5% 4 6% 8% 47%	2289
October	1st to 10th	Day	9% 4 2 5% 3 3 3 3 4 7% 57%	3518
	11th to 20th	Day	12% 7% 3 6% 4 5% 5% 3 6% 7% 42%	3015
	21st to end	Day	19% 11% 3 8% 4 5% 6% 4 5% 5% 30%	3200
November	1st to 10th	Day	27% 14% 3 6% 5% 5% 3 3 4 6% 23%	1854
	11th to 20th	Day	24% 16% 5% 9% 5% 4 4 4 4 4 22%	1820
	21st to end	Day	20% 19% 6% 10% 5% 5% 4 4 4 4 21%	1480
December	1st to 10th	Day	16% 14% 6% 11% 6% 4 5% 4 6% 7% 23%	2360
	11th to 20th	Day	20% 24% 6% 12% 6% 5% 4 4 3 4 11%	2712
	21st to end	Day	20% 24% 7% 11% 5% 5% 5% 3 3 5% 13%	3640
January	1st to 10th	Night	21% 21% 5% 11% 6% 6% 6% 4 5% 4 12%	8172
	11th to 20th	Night	12% 10% 3 8% 6% 5% 7% 6% 7% 7% 29%	8182
	21st to end	Night	18% 13% 4 7% 5% 4 4 4 10% 6% 26%	8994
February	1st to 10th	Night	20% 18% 5% 7% 5% 4 3 3 5% 5% 24%	2940
	11th to 20th	Night	16% 16% 4 8% 5% 4 3 3 4 6% 28%	2534
	21st to end	Night	14% 15% 4 9% 6% 5% 4 4 5% 6% 28%	2076
March	1st to 10th	Night	9% 11% 3 7% 4 4 5% 4 5% 7% 40%	5496
	11th to 20th	Night	13% 12% 4 8% 4 4 4 3 4 5% 40%	5381
	21st to end	Night	15% 11% 3 9% 6% 6% 6% 5% 8% 8% 23%	5234
April	1st to 10th	Night	11% 10% 3 7% 5% 5% 5% 4 7% 9% 34%	2100
	11th to 20th	Night	13% 10% 2 7% 5% 5% 4 3 5% 6% 41%	1981
	21st to end	Night	11% 8% 3 7% 5% 5% 6% 4 6% 6% 39%	1890
May	1st to 10th	Night	8% 5% 2 4 4 5% 5% 4 6% 8% 50%	4974
	11th to 20th	Night	11% 8% 3 7% 5% 5% 5% 4 7% 9% 38%	4700
	21st to end	Night	11% 5% 3 7% 5% 5% 5% 4 5% 8% 43%	4962
June	1st to 10th	Night	12% 5% 3 7% 4 4 4 4 6% 7% 44%	1470
	11th to 20th	Night	10% 5% 2 6% 4 4 6% 4 6% 8% 44%	1470
	21st to end	Night	7% 5% 2 5% 4 4 5% 3 5% 7% 53%	1470
July	1st to 10th	Night	3 1 1 2 2 2 2 2 4 5% 75%	4491
	11th to 20th	Night	2 1 1 3 2 2 3 2 4 5% 75%	4740
	21st to end	Night	3 2 1 3 2 2 2 2 3 5% 74%	5152
August	1st to 10th	Night	2 2 1 2 1 2 2 2 4 5% 77%	3709
	11th to 20th	Night	2 2 1 3 2 3 3 3 5% 7% 67%	4021
	21st to end	Night	4 3 1 4 3 4 4 3 5% 7% 63%	4881
September	1st to 10th	Night	6% 2 1 4 3 2 3 3 5% 8% 63%	2100
	11th to 20th	Night	7% 5% 2 5% 5% 4 4 4 5% 7% 51%	2242
	21st to end	Night	11% 4 2 5% 4 4 3 3 5% 6% 54%	2288
October	1st to 10th	Night	8% 4 1 4 2 3 4 3 5% 7% 60%	3680
	11th to 20th	Night	12% 5% 2 5% 4 4 5% 3 5% 7% 49%	4134
	21st to end	Night	14% 7% 2 6% 4 4 6% 5% 6% 7% 40%	4600
November	1st to 10th	Night	24% 12% 3 6% 4 4 5% 4 6% 7% 27%	2665
	11th to 20th	Night	23% 14% 4 9% 5% 5% 5% 4 4 5% 23%	2798
	21st to end	Night	23% 14% 4 8% 5% 5% 4 4 5% 6% 24%	3115
December	1st to 10th	Night	13% 11% 4 9% 6% 5% 7% 5% 7% 6% 27%	5040
	11th to 20th	Night	19% 21% 6% 12% 6% 5% 5% 4 5% 5% 13%	5700
	21st to end	Night	19% 20% 7% 12% 6% 6% 5% 4 4 5% 13%	7599

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	78% 7% 8% 6% 1	4723
	11th to 20th	Day	51% 7% 19% 17% 5% 1	4740
	21st to end	Day	57% 6% 16% 15% 5%	5187
February	1st to 10th	Day	67% 7% 11% 9% 5% 1	1680
	11th to 20th	Day	63% 8% 11% 11% 6%	1979
	21st to end	Day	65% 6% 9% 15% 5%	1730
March	1st to 10th	Day	48% 7% 13% 19% 13%	4618
	11th to 20th	Day	49% 5% 15% 27% 3	4838
	21st to end	Day	64% 8% 11% 13% 4	5979
April	1st to 10th	Day	57% 7% 18% 15% 4	2520
	11th to 20th	Day	50% 7% 14% 18% 10% 1	2590
	21st to end	Day	49% 9% 13% 20% 8% 1	2730
May	1st to 10th	Day	31% 5% 12% 35% 16%	7942
	11th to 20th	Day	38% 7% 17% 30% 8%	8163
	21st to end	Day	37% 8% 19% 29% 7%	9210
June	1st to 10th	Day	45% 6% 13% 22% 13% 1	3150
	11th to 20th	Day	41% 7% 13% 22% 13% 3	3150
	21st to end	Day	29% 6% 14% 29% 19% 3	3150
July	1st to 10th	Day	15% 3 8% 26% 32% 17%	8395
	11th to 20th	Day	16% 2 5% 21% 30% 26%	8145
	21st to end	Day	13% 2 5% 29% 35% 17%	8723
August	1st to 10th	Day	13% 2 4 23% 38% 20%	6424
	11th to 20th	Day	17% 4 9% 45% 22% 3	6078
	21st to end	Day	18% 3 11% 38% 27% 3	6264
September	1st to 10th	Day	21% 5% 12% 30% 23% 10%	2520
	11th to 20th	Day	33% 6% 12% 25% 21% 3	2378
	21st to end	Day	35% 7% 17% 25% 12% 3	2289
October	1st to 10th	Day	29% 4 13% 37% 16%	3518
	11th to 20th	Day	41% 6% 18% 24% 11% 1	3015
	21st to end	Day	54% 7% 15% 18% 6%	3200
November	1st to 10th	Day	63% 7% 13% 13% 3	1854
	11th to 20th	Day	67% 8% 12% 9% 3 1	1820
	21st to end	Day	67% 6% 10% 12% 4	1480
December	1st to 10th	Day	62% 9% 16% 11% 2	2360
	11th to 20th	Day	78% 6% 8% 7% 1	2714
	21st to end	Day	75% 6% 9% 7% 3	3640
January	1st to 10th	Night	74% 8% 10% 7% 1	8172
	11th to 20th	Night	51% 10% 18% 14% 6% 1	8220
	21st to end	Night	55% 7% 16% 18% 4	8994
February	1st to 10th	Night	63% 7% 13% 11% 5% 1	2940
	11th to 20th	Night	58% 6% 15% 13% 7% 1	2535
	21st to end	Night	57% 7% 12% 16% 6% 1	2076
March	1st to 10th	Night	42% 6% 13% 24% 14% 1	5496
	11th to 20th	Night	48% 5% 13% 27% 7%	5381
	21st to end	Night	56% 11% 14% 17% 3	5234
April	1st to 10th	Night	46% 8% 15% 23% 8%	2100
	11th to 20th	Night	45% 5% 12% 22% 14% 1	1981
	21st to end	Night	43% 8% 12% 24% 12% 1	1890
May	1st to 10th	Night	31% 6% 8% 34% 21% 1	4971
	11th to 20th	Night	39% 7% 13% 27% 14%	4700
	21st to end	Night	37% 10% 13% 30% 10%	4966
June	1st to 10th	Night	39% 8% 10% 24% 18% 2	1470
	11th to 20th	Night	37% 6% 11% 23% 19% 4	1470
	21st to end	Night	29% 5% 11% 27% 21% 6%	1470
July	1st to 10th	Night	14% 2 6% 21% 36% 22%	4451
	11th to 20th	Night	12% 1 5% 17% 31% 33%	4692
	21st to end	Night	14% 2 4 21% 36% 24%	5040
August	1st to 10th	Night	11% 2 4 14% 37% 31%	3701
	11th to 20th	Night	17% 4 6% 40% 26% 6%	4047
	21st to end	Night	20% 4 9% 28% 33% 6%	4881
September	1st to 10th	Night	20% 5% 9% 27% 28% 12%	2100
	11th to 20th	Night	31% 6% 9% 24% 23% 6%	2242
	21st to end	Night	31% 5% 15% 28% 17% 5%	2288
October	1st to 10th	Night	25% 4 11% 41% 18% 1	3680
	11th to 20th	Night	36% 4 15% 24% 19% 1	4134
	21st to end	Night	40% 8% 14% 27% 8% 2	4600
November	1st to 10th	Night	56% 8% 17% 14% 4 1	2665
	11th to 20th	Night	62% 8% 13% 11% 5% 1	2798
	21st to end	Night	61% 7% 14% 13% 5%	3115
December	1st to 10th	Night	57% 10% 17% 14% 2	5040
	11th to 20th	Night	73% 7% 11% 7% 1	5697
	21st to end	Night	72% 9% 10% 8% 2	7599

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	31% 17% 19% 20% 11% 2	220
	11th to 20th	Day	30% 14% 16% 21% 14% 5%	220
	21st to end	Day	29% 10% 24% 21% 13% 3	242
February	1st to 10th	Day	30% 17% 27% 15% 8% 4	220
	11th to 20th	Day	31% 14% 23% 21% 11% 1	479
	21st to end	Day	28% 18% 22% 21% 10% 1	446
March	1st to 10th	Day	25% 20% 23% 19% 10% 3	540
	11th to 20th	Day	25% 15% 21% 22% 14% 2	540
	21st to end	Day	26% 18% 26% 19% 10% 1	594
April	1st to 10th	Day	23% 15% 26% 21% 9% 6%	540
	11th to 20th	Day	16% 21% 27% 19% 12% 4	532
	21st to end	Day	17% 15% 25% 25% 14% 5%	540
May	1st to 10th	Day	12% 12% 26% 31% 15% 5%	543
	11th to 20th	Day	18% 11% 29% 23% 15% 5%	568
	21st to end	Day	13% 9% 21% 29% 18% 9%	690
June	1st to 10th	Day	17% 9% 24% 25% 20% 5%	780
	11th to 20th	Day	16% 13% 30% 25% 14% 3	780
	21st to end	Day	8% 8% 24% 29% 24% 6%	780
July	1st to 10th	Day	5% 6% 23% 34% 26% 5%	654
	11th to 20th	Day	4 9% 27% 34% 21% 5%	564
	21st to end	Day	3 7% 23% 35% 25% 8%	619
August	1st to 10th	Day	6% 6% 22% 34% 24% 8%	567
	11th to 20th	Day	4 3 21% 36% 25% 10%	557
	21st to end	Day	7% 8% 27% 25% 20% 13%	627
September	1st to 10th	Day	9% 8% 24% 26% 21% 12%	570
	11th to 20th	Day	12% 11% 22% 25% 21% 9%	570
	21st to end	Day	12% 11% 25% 23% 21% 7%	563
October	1st to 10th	Day	14% 8% 26% 26% 18% 7%	530
	11th to 20th	Day	20% 14% 22% 22% 13% 8%	387
	21st to end	Day	29% 11% 23% 23% 13% 3	363
November	1st to 10th	Day	34% 12% 18% 25% 10% 1	330
	11th to 20th	Day	35% 11% 20% 17% 15% 1	292
	21st to end	Day	27% 14% 20% 24% 13% 1	220
December	1st to 10th	Day	30% 13% 21% 15% 16% 5%	220
	11th to 20th	Day	38% 13% 23% 15% 10% 2	220
	21st to end	Day	37% 12% 19% 20% 10% 2	242
January	1st to 10th	Night	40% 9% 16% 24% 10% 2	840
	11th to 20th	Night	29% 8% 16% 32% 14% 2	840
	21st to end	Night	27% 6% 17% 32% 16% 2	924
February	1st to 10th	Night	32% 9% 21% 25% 11% 2	840
	11th to 20th	Night	28% 8% 17% 31% 15% 1	824
	21st to end	Night	23% 11% 21% 27% 17% 2	692
March	1st to 10th	Night	22% 10% 19% 31% 17% 1	840
	11th to 20th	Night	25% 10% 16% 31% 18% 1	840
	21st to end	Night	23% 8% 23% 33% 12% 2	924
April	1st to 10th	Night	17% 7% 18% 37% 18% 2	840
	11th to 20th	Night	17% 8% 24% 33% 16% 1	733
	21st to end	Night	15% 8% 20% 33% 22% 2	630
May	1st to 10th	Night	11% 5% 20% 34% 26% 3	514
	11th to 20th	Night	11% 6% 18% 30% 28% 6%	414
	21st to end	Night	15% 5% 16% 28% 31% 5%	455
June	1st to 10th	Night	14% 4 19% 35% 24% 4	420
	11th to 20th	Night	13% 6% 23% 34% 22% 2	420
	21st to end	Night	7% 4 12% 40% 32% 5%	420
July	1st to 10th	Night	3 1 11% 40% 41% 2	410
	11th to 20th	Night	3 3 13% 48% 31% 2	408
	21st to end	Night	2 2 10% 41% 42% 3	460
August	1st to 10th	Night	3 3 9% 40% 39% 6%	418
	11th to 20th	Night	3 1 8% 39% 40% 8%	567
	21st to end	Night	5% 4 13% 36% 39% 3	827
September	1st to 10th	Night	7% 2 13% 38% 34% 6%	840
	11th to 20th	Night	9% 4 14% 31% 34% 8%	840
	21st to end	Night	12% 5% 17% 34% 27% 5%	832
October	1st to 10th	Night	15% 5% 13% 40% 26% 2	800
	11th to 20th	Night	20% 6% 16% 31% 25% 3	800
	21st to end	Night	21% 8% 19% 32% 17% 3	880
November	1st to 10th	Night	31% 8% 14% 34% 13%	820
	11th to 20th	Night	33% 9% 17% 27% 14% 1	840
	21st to end	Night	31% 8% 15% 28% 16% 2	1015
December	1st to 10th	Night	27% 9% 17% 30% 17% 1	1050
	11th to 20th	Night	36% 8% 19% 28% 9%	1050
	21st to end	Night	36% 11% 18% 26% 9%	1144

Page generated at 2026-09-26 01:18:41. Version ac07

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