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 2024-11-02.

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	13% 9% 3 6% 4 4 4 3 5% 6% 43%	101421
	Night	15% 10% 3 7% 4 4 4 3 5% 6% 38%	97629
Transparency	Day	42% 6% 12% 21% 14% 5%	101189
	Night	46% 7% 12% 19% 12% 5%	97507
Seeing	Day	18% 12% 24% 25% 16% 5%	14888
	Night	21% 7% 17% 32% 21% 3	24014

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	24% 27% 6% 9% 4 5% 3 3 4 4 11%	2539
	11th to 20th	Day	24% 15% 4 8% 6% 6% 4 4 5% 6% 20%	2516
	21st to end	Day	27% 19% 5% 8% 5% 4 5% 3 4 4 15%	2794
February	1st to 10th	Day	23% 18% 5% 7% 5% 4 4 4 5% 5% 20%	1520
	11th to 20th	Day	18% 19% 5% 8% 4 4 4 3 4 6% 24%	1775
	21st to end	Day	19% 21% 5% 9% 6% 4 4 3 4 4 22%	1570
March	1st to 10th	Day	13% 16% 4 8% 6% 6% 5% 4 5% 7% 28%	3138
	11th to 20th	Day	12% 10% 3 6% 4 4 4 3 4 5% 45%	3301
	21st to end	Day	19% 16% 4 10% 6% 6% 5% 4 5% 5% 20%	4085
April	1st to 10th	Day	16% 15% 3 8% 5% 5% 5% 4 6% 7% 23%	2280
	11th to 20th	Day	13% 10% 4 8% 7% 5% 5% 4 5% 6% 32%	2340
	21st to end	Day	14% 10% 2 9% 6% 5% 5% 4 6% 7% 33%	2470
May	1st to 10th	Day	11% 8% 3 8% 5% 5% 5% 4 6% 7% 37%	4284
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 11% 45%	4377
	21st to end	Day	12% 7% 3 7% 6% 6% 6% 5% 6% 8% 33%	4931
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	14% 7% 2 7% 4 3 3 3 4 6% 47%	2047
	11th to 20th	Day	17% 8% 3 5% 4 3 4 3 5% 5% 43%	1764
	21st to end	Day	21% 10% 3 7% 4 4 5% 4 5% 5% 34%	1881
November	1st to 10th	Day	28% 15% 3 6% 4 4 3 3 4 6% 23%	1683
	11th to 20th	Day	24% 16% 4 9% 5% 4 4 4 3 4 23%	1648
	21st to end	Day	20% 19% 6% 9% 5% 5% 3 4 4 4 22%	1340
December	1st to 10th	Day	20% 17% 7% 10% 5% 4 4 3 5% 5% 20%	1330
	11th to 20th	Day	25% 23% 6% 11% 5% 4 3 4 3 4 11%	1682
	21st to end	Day	20% 21% 5% 11% 5% 5% 5% 3 4 5% 17%	2478
January	1st to 10th	Night	27% 23% 5% 8% 5% 5% 4 3 3 4 13%	4406
	11th to 20th	Night	20% 15% 4 9% 5% 4 4 3 5% 7% 24%	4382
	21st to end	Night	29% 18% 4 7% 4 4 3 3 4 5% 18%	4862
February	1st to 10th	Night	22% 19% 4 6% 4 4 3 3 5% 5% 25%	2660
	11th to 20th	Night	17% 15% 4 8% 5% 5% 4 3 5% 5% 29%	2288
	21st to end	Night	14% 16% 4 9% 6% 5% 4 4 5% 6% 28%	1884
March	1st to 10th	Night	11% 12% 3 8% 5% 4 5% 4 5% 6% 36%	3736
	11th to 20th	Night	13% 10% 2 5% 3 3 3 3 4 4 49%	3677
	21st to end	Night	16% 11% 3 9% 6% 6% 6% 5% 7% 6% 24%	3564
April	1st to 10th	Night	12% 11% 3 7% 5% 5% 5% 4 7% 9% 33%	1900
	11th to 20th	Night	13% 10% 2 7% 6% 5% 4 3 5% 6% 39%	1791
	21st to end	Night	12% 9% 3 7% 5% 4 6% 4 6% 6% 39%	1710
May	1st to 10th	Night	12% 8% 3 6% 6% 6% 6% 4 6% 8% 36%	2678
	11th to 20th	Night	7% 5% 2 5% 4 4 4 4 6% 9% 47%	2516
	21st to end	Night	16% 6% 3 7% 6% 6% 5% 5% 6% 7% 33%	2644
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	12% 6% 1 6% 3 4 4 3 5% 7% 49%	2132
	11th to 20th	Night	15% 6% 3 6% 4 4 4 3 4 7% 44%	2415
	21st to end	Night	18% 7% 2 6% 4 3 4 3 5% 6% 40%	2717
November	1st to 10th	Night	25% 12% 3 6% 3 4 4 4 6% 7% 26%	2418
	11th to 20th	Night	23% 15% 3 8% 5% 5% 5% 4 4 5% 24%	2531
	21st to end	Night	22% 13% 3 7% 5% 4 4 4 5% 6% 25%	2817
December	1st to 10th	Night	20% 15% 5% 9% 5% 4 4 3 5% 5% 25%	2850
	11th to 20th	Night	24% 19% 5% 10% 6% 5% 5% 3 4 4 14%	3510
	21st to end	Night	21% 17% 5% 10% 6% 6% 6% 4 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	55% 8% 11% 16% 10%	3138
	11th to 20th	Day	43% 6% 17% 31% 3	3302
	21st to end	Day	66% 9% 11% 9% 5%	4085
April	1st to 10th	Day	59% 7% 17% 14% 4	2280
	11th to 20th	Day	51% 7% 14% 17% 10% 1	2340
	21st to end	Day	51% 9% 13% 19% 7% 1	2470
May	1st to 10th	Day	44% 8% 12% 28% 7%	4284
	11th to 20th	Day	32% 7% 19% 33% 8% 1	4380
	21st to end	Day	45% 11% 18% 22% 4	4932
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	40% 5% 13% 30% 11%	2047
	11th to 20th	Day	44% 6% 15% 26% 9% 1	1764
	21st to end	Day	52% 7% 15% 19% 6%	1881
November	1st to 10th	Day	64% 7% 13% 12% 3	1683
	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	46% 8% 12% 25% 9% 1	3736
	11th to 20th	Night	39% 6% 17% 32% 6%	3677
	21st to end	Night	56% 11% 14% 15% 4	3564
April	1st to 10th	Night	46% 9% 15% 23% 7%	1900
	11th to 20th	Night	47% 5% 12% 21% 13% 1	1791
	21st to end	Night	44% 8% 12% 24% 11% 1	1710
May	1st to 10th	Night	43% 9% 13% 24% 11% 1	2678
	11th to 20th	Night	29% 8% 13% 33% 17% 1	2516
	21st to end	Night	44% 13% 14% 20% 9%	2644
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	35% 5% 11% 34% 15% 1	2132
	11th to 20th	Night	42% 5% 13% 23% 15% 1	2415
	21st to end	Night	44% 9% 13% 22% 10% 1	2717
November	1st to 10th	Night	57% 8% 15% 15% 4 1	2418
	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% 18% 10% 2	460
	11th to 20th	Day	22% 14% 22% 23% 16% 2	460
	21st to end	Day	28% 18% 25% 20% 8% 1	506
April	1st to 10th	Day	25% 15% 29% 21% 7% 3	460
	11th to 20th	Day	17% 22% 27% 19% 12% 3	452
	21st to end	Day	18% 16% 27% 25% 12% 2	460
May	1st to 10th	Day	14% 14% 26% 30% 13% 3	463
	11th to 20th	Day	19% 10% 26% 23% 16% 5%	488
	21st to end	Day	14% 10% 22% 29% 18% 7%	595
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% 12% 22% 22% 11% 3	330
November	1st to 10th	Day	37% 12% 16% 26% 8%	273
	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% 18% 31% 17% 1	760
	11th to 20th	Night	23% 10% 16% 31% 19% 1	760
	21st to end	Night	23% 8% 22% 33% 12% 2	836
April	1st to 10th	Night	18% 7% 19% 37% 18% 2	760
	11th to 20th	Night	18% 8% 24% 32% 16% 2	663
	21st to end	Night	16% 8% 22% 32% 20% 2	570
May	1st to 10th	Night	11% 6% 22% 32% 26% 3	466
	11th to 20th	Night	10% 5% 18% 30% 30% 7%	374
	21st to end	Night	15% 5% 16% 28% 30% 5%	411
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% 4	836
November	1st to 10th	Night	33% 7% 14% 34% 12%	744
	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 2024-10-29 22:22:54. Version ac07

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