Idaho City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Idaho City 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	6% 8% 3 6% 4 3 4 3 5% 6% 52%	157829
	Night	7% 9% 3 6% 4 4 4 3 5% 6% 50%	150962
Transparency	Day	32% 5% 7% 21% 22% 13%	152588
	Night	34% 5% 9% 23% 19% 11%	147205
Seeing	Day	14% 12% 29% 28% 14% 3	16862
	Night	14% 4 17% 40% 22% 3	26106

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	8% 23% 9% 14% 5% 5% 4 3 4 4 21%	4722
	11th to 20th	Day	5% 11% 6% 6% 3 3 2 2 4 6% 52%	4740
	21st to end	Day	8% 12% 3 7% 5% 5% 4 3 4 6% 44%	5187
February	1st to 10th	Day	11% 18% 6% 10% 6% 4 3 3 4 5% 30%	1843
	11th to 20th	Day	9% 22% 5% 8% 5% 5% 5% 3 4 6% 28%	2050
	21st to end	Day	8% 20% 7% 10% 7% 5% 4 4 5% 5% 26%	1730
March	1st to 10th	Day	5% 14% 6% 12% 5% 5% 4 4 6% 8% 31%	4618
	11th to 20th	Day	6% 14% 4 10% 5% 4 4 3 4 5% 42%	4961
	21st to end	Day	9% 18% 5% 11% 6% 6% 5% 4 5% 7% 23%	5817
April	1st to 10th	Day	10% 15% 5% 8% 5% 4 3 4 6% 7% 33%	2520
	11th to 20th	Day	9% 13% 3 7% 5% 5% 5% 3 5% 6% 38%	2560
	21st to end	Day	9% 12% 3 7% 5% 4 5% 4 5% 6% 39%	2730
May	1st to 10th	Day	5% 8% 2 5% 4 3 4 3 5% 5% 56%	7626
	11th to 20th	Day	6% 7% 2 5% 4 4 4 3 5% 6% 53%	7782
	21st to end	Day	5% 5% 2 5% 4 4 4 4 5% 7% 56%	8992
June	1st to 10th	Day	11% 6% 2 7% 5% 4 4 4 6% 7% 43%	2940
	11th to 20th	Day	9% 6% 2 4 4 4 4 3 5% 7% 52%	2940
	21st to end	Day	3 3 1 4 3 2 3 3 4 5% 67%	2940
July	1st to 10th	Day	2 1 1 2 2 2 2 2 4 5% 77%	8219
	11th to 20th	Day	2 3 1 3 2 2 3 2 4 5% 73%	8220
	21st to end	Day	2 3 1 3 2 3 3 3 5% 7% 68%	8922
August	1st to 10th	Day	1 2 1 3 3 3 3 3 4 6% 70%	7758
	11th to 20th	Day	1 2 1 3 2 2 3 2 4 6% 73%	7565
	21st to end	Day	5% 4 2 5% 4 3 4 3 4 5% 61%	7869
September	1st to 10th	Day	4 3 1 3 2 3 3 3 4 7% 69%	2520
	11th to 20th	Day	6% 4 2 5% 3 3 3 3 4 6% 59%	2310
	21st to end	Day	7% 6% 2 4 2 2 4 2 5% 6% 62%	2289
October	1st to 10th	Day	5% 5% 2 5% 3 3 3 2 3 5% 64%	3600
	11th to 20th	Day	8% 6% 2 6% 4 4 4 3 4 6% 54%	3141
	21st to end	Day	7% 10% 3 9% 5% 4 3 3 5% 7% 44%	3200
November	1st to 10th	Day	13% 13% 3 7% 4 4 4 3 5% 7% 37%	1854
	11th to 20th	Day	14% 13% 4 7% 5% 4 5% 4 5% 6% 33%	1890
	21st to end	Day	10% 12% 4 8% 4 5% 4 4 4 7% 38%	1874
December	1st to 10th	Day	9% 10% 3 5% 3 3 3 2 3 5% 53%	2700
	11th to 20th	Day	12% 19% 6% 10% 5% 5% 4 4 6% 6% 23%	3108
	21st to end	Day	12% 17% 6% 10% 5% 4 4 3 5% 6% 29%	4092
January	1st to 10th	Night	9% 20% 6% 11% 5% 5% 4 3 5% 5% 26%	8172
	11th to 20th	Night	7% 11% 4 6% 3 3 3 2 4 5% 51%	8220
	21st to end	Night	7% 10% 3 7% 4 4 4 3 6% 7% 43%	8994
February	1st to 10th	Night	12% 18% 4 8% 5% 4 3 3 4 6% 32%	2771
	11th to 20th	Night	10% 17% 4 8% 4 3 4 3 5% 7% 35%	2458
	21st to end	Night	10% 17% 5% 10% 5% 4 5% 3 5% 5% 31%	2076
March	1st to 10th	Night	6% 14% 4 8% 5% 4 3 3 4 8% 41%	5496
	11th to 20th	Night	8% 16% 4 8% 4 3 3 3 4 5% 42%	5258
	21st to end	Night	6% 12% 4 8% 5% 5% 6% 5% 8% 9% 33%	5397
April	1st to 10th	Night	10% 10% 2 7% 4 4 4 4 6% 7% 42%	2100
	11th to 20th	Night	9% 9% 3 6% 4 5% 5% 3 5% 5% 45%	2008
	21st to end	Night	7% 6% 3 6% 4 4 4 3 5% 7% 49%	1890
May	1st to 10th	Night	5% 6% 1 3 2 3 3 3 5% 7% 61%	5321
	11th to 20th	Night	5% 5% 2 6% 4 4 4 4 4 6% 58%	5081
	21st to end	Night	4 4 1 5% 3 4 4 3 5% 7% 59%	5181
June	1st to 10th	Night	10% 4 2 5% 5% 4 5% 3 7% 9% 46%	1680
	11th to 20th	Night	7% 5% 2 4 3 3 4 3 5% 6% 59%	1680
	21st to end	Night	3 3 2 3 3 4 4 4 5% 6% 64%	1680
July	1st to 10th	Night	2 2 1 2 2 2 3 2 4 5% 74%	4740
	11th to 20th	Night	1 2 1 2 2 2 3 2 4 5% 74%	4740
	21st to end	Night	2 2 1 4 3 3 3 3 5% 8% 65%	5153
August	1st to 10th	Night	2 2 1 4 3 3 3 2 4 6% 71%	5053
	11th to 20th	Night	1 1 1 3 2 3 4 3 6% 6% 70%	5291
	21st to end	Night	5% 4 2 5% 3 3 4 4 5% 6% 59%	6358
September	1st to 10th	Night	3 2 1 3 2 3 2 2 4 5% 72%	2100
	11th to 20th	Night	6% 3 2 4 3 3 4 3 5% 6% 61%	2309
	21st to end	Night	7% 3 2 3 2 2 2 3 4 5% 66%	2288
October	1st to 10th	Night	5% 3 1 4 3 2 3 2 4 6% 67%	3600
	11th to 20th	Night	7% 5% 2 5% 3 4 3 3 4 6% 59%	4007
	21st to end	Night	8% 9% 2 6% 4 4 5% 4 6% 8% 45%	4600
November	1st to 10th	Night	13% 10% 2 6% 4 4 4 3 6% 7% 41%	2665
	11th to 20th	Night	15% 11% 3 6% 5% 5% 4 4 5% 6% 36%	2730
	21st to end	Night	10% 13% 3 6% 4 4 4 3 4 7% 41%	2743
December	1st to 10th	Night	9% 9% 3 5% 3 4 3 3 4 6% 52%	4700
	11th to 20th	Night	10% 19% 5% 11% 6% 4 5% 4 6% 7% 23%	5316
	21st to end	Night	12% 15% 5% 10% 5% 5% 4 4 6% 6% 27%	7106

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	65% 7% 10% 15% 4	4723
	11th to 20th	Day	34% 4 12% 36% 12% 2	4740
	21st to end	Day	42% 4 11% 23% 16% 3	5187
February	1st to 10th	Day	56% 5% 14% 19% 6% 1	1843
	11th to 20th	Day	57% 7% 11% 17% 8% 1	2060
	21st to end	Day	57% 7% 9% 17% 10% 2	1730
March	1st to 10th	Day	48% 7% 8% 21% 13% 4	4618
	11th to 20th	Day	42% 6% 8% 30% 14% 1	4961
	21st to end	Day	54% 9% 12% 17% 7%	5817
April	1st to 10th	Day	48% 6% 12% 21% 11% 2	2520
	11th to 20th	Day	45% 4 10% 23% 16% 2	2563
	21st to end	Day	42% 6% 10% 24% 17%	2730
May	1st to 10th	Day	28% 4 5% 28% 31% 4	7626
	11th to 20th	Day	28% 5% 5% 25% 29% 7%	7785
	21st to end	Day	24% 6% 7% 32% 28% 4	8994
June	1st to 10th	Day	37% 7% 9% 26% 19% 2	2940
	11th to 20th	Day	30% 4 5% 23% 28% 9%	2940
	21st to end	Day	19% 4 4 19% 36% 18%	2940
July	1st to 10th	Day	10% 3 2 12% 27% 46%	8151
	11th to 20th	Day	14% 2 2 9% 25% 48%	8145
	21st to end	Day	14% 4 3 14% 33% 33%	8723
August	1st to 10th	Day	16% 4 3 8% 25% 45%	6138
	11th to 20th	Day	15% 4 4 17% 38% 22%	5964
	21st to end	Day	22% 3 3 20% 31% 21%	6172
September	1st to 10th	Day	16% 3 4 18% 33% 26%	2520
	11th to 20th	Day	25% 4 6% 24% 28% 13%	2310
	21st to end	Day	24% 4 4 26% 31% 11%	2289
October	1st to 10th	Day	24% 3 5% 17% 39% 11%	3600
	11th to 20th	Day	32% 4 10% 25% 26% 4	3141
	21st to end	Day	38% 6% 8% 26% 22% 1	3200
November	1st to 10th	Day	45% 6% 12% 21% 15% 1	1854
	11th to 20th	Day	50% 6% 16% 20% 8%	1890
	21st to end	Day	46% 5% 13% 24% 10% 2	1874
December	1st to 10th	Day	34% 3 15% 39% 7% 1	2700
	11th to 20th	Day	59% 6% 16% 15% 4	3108
	21st to end	Day	55% 5% 13% 20% 8%	4092
January	1st to 10th	Night	57% 8% 14% 17% 4	8172
	11th to 20th	Night	36% 4 11% 32% 13% 3	8220
	21st to end	Night	38% 7% 10% 28% 12% 4	8994
February	1st to 10th	Night	52% 6% 14% 21% 5% 1	2771
	11th to 20th	Night	48% 6% 14% 20% 11% 1	2459
	21st to end	Night	53% 6% 9% 19% 12% 2	2076
March	1st to 10th	Night	41% 6% 8% 25% 15% 6%	5496
	11th to 20th	Night	43% 4 6% 27% 17% 2	5258
	21st to end	Night	42% 10% 17% 23% 9% 1	5397
April	1st to 10th	Night	40% 6% 11% 27% 15% 2	2100
	11th to 20th	Night	39% 5% 10% 26% 19% 2	2008
	21st to end	Night	33% 4 12% 29% 20% 1	1890
May	1st to 10th	Night	22% 4 6% 30% 33% 5%	5319
	11th to 20th	Night	25% 5% 5% 29% 31% 4	5082
	21st to end	Night	22% 5% 8% 33% 28% 4	5182
June	1st to 10th	Night	33% 5% 12% 28% 20% 2	1680
	11th to 20th	Night	25% 5% 6% 23% 31% 9%	1680
	21st to end	Night	20% 4 5% 19% 35% 18%	1680
July	1st to 10th	Night	12% 3 2 11% 26% 46%	4700
	11th to 20th	Night	12% 3 2 8% 24% 51%	4692
	21st to end	Night	17% 4 3 12% 29% 35%	5040
August	1st to 10th	Night	16% 3 2 7% 22% 50%	4000
	11th to 20th	Night	15% 5% 5% 13% 34% 29%	4168
	21st to end	Night	22% 5% 3 19% 28% 24%	4977
September	1st to 10th	Night	16% 2 4 16% 34% 28%	2100
	11th to 20th	Night	23% 4 6% 20% 29% 18%	2309
	21st to end	Night	22% 3 3 25% 32% 15%	2288
October	1st to 10th	Night	19% 3 5% 21% 32% 19%	3600
	11th to 20th	Night	27% 4 10% 25% 27% 7%	4007
	21st to end	Night	35% 6% 11% 26% 19% 3	4600
November	1st to 10th	Night	42% 4 12% 22% 18% 2	2665
	11th to 20th	Night	47% 6% 12% 24% 10%	2730
	21st to end	Night	44% 4 13% 25% 12% 2	2743
December	1st to 10th	Night	32% 5% 17% 35% 9% 1	4700
	11th to 20th	Night	58% 6% 13% 18% 4 1	5316
	21st to end	Night	53% 6% 13% 19% 7% 1	7106

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	24% 10% 27% 20% 17% 3	220
	11th to 20th	Day	17% 8% 25% 26% 17% 7%	220
	21st to end	Day	14% 7% 26% 29% 18% 6%	242
February	1st to 10th	Day	25% 12% 25% 23% 12% 3	321
	11th to 20th	Day	21% 14% 33% 23% 8% 1	535
	21st to end	Day	22% 16% 30% 24% 7% 2	446
March	1st to 10th	Day	21% 17% 34% 22% 5% 1	540
	11th to 20th	Day	21% 15% 30% 21% 11% 2	540
	21st to end	Day	23% 18% 29% 22% 7% 1	594
April	1st to 10th	Day	21% 16% 27% 24% 11% 1	540
	11th to 20th	Day	19% 19% 33% 20% 8% 1	532
	21st to end	Day	19% 17% 31% 22% 8% 2	540
May	1st to 10th	Day	17% 13% 33% 25% 11% 1	543
	11th to 20th	Day	22% 16% 27% 24% 8% 3	568
	21st to end	Day	16% 10% 26% 28% 14% 6%	617
June	1st to 10th	Day	14% 13% 30% 24% 16% 4	570
	11th to 20th	Day	16% 14% 34% 24% 10% 2	570
	21st to end	Day	8% 11% 31% 31% 17% 2	570
July	1st to 10th	Day	4 8% 34% 37% 14% 3	566
	11th to 20th	Day	3 10% 36% 33% 15% 3	564
	21st to end	Day	3 6% 34% 36% 16% 5%	619
August	1st to 10th	Day	5% 8% 33% 33% 17% 4	567
	11th to 20th	Day	3 10% 28% 33% 21% 5%	557
	21st to end	Day	6% 11% 29% 31% 18% 5%	627
September	1st to 10th	Day	6% 9% 24% 37% 18% 5%	570
	11th to 20th	Day	9% 8% 29% 33% 18% 3	570
	21st to end	Day	9% 10% 31% 29% 18% 3	563
October	1st to 10th	Day	12% 10% 25% 29% 18% 6%	530
	11th to 20th	Day	14% 10% 27% 26% 17% 7%	394
	21st to end	Day	18% 10% 22% 30% 17% 2	363
November	1st to 10th	Day	22% 6% 23% 32% 14% 3	330
	11th to 20th	Day	18% 11% 22% 31% 15% 4	330
	21st to end	Day	16% 6% 25% 30% 18% 4	322
December	1st to 10th	Day	27% 6% 20% 20% 17% 10%	220
	11th to 20th	Day	26% 9% 23% 26% 13% 4	220
	21st to end	Day	21% 8% 24% 31% 13% 3	242
January	1st to 10th	Night	23% 5% 19% 33% 19% 3	840
	11th to 20th	Night	22% 3 20% 33% 18% 3	840
	21st to end	Night	18% 3 16% 40% 20% 3	924
February	1st to 10th	Night	23% 3 21% 35% 16% 2	840
	11th to 20th	Night	17% 5% 21% 36% 18% 3	824
	21st to end	Night	19% 6% 19% 38% 15% 3	692
March	1st to 10th	Night	18% 6% 21% 39% 14% 2	840
	11th to 20th	Night	19% 5% 20% 37% 19% 2	840
	21st to end	Night	19% 7% 20% 38% 15% 2	924
April	1st to 10th	Night	16% 6% 18% 40% 19% 2	840
	11th to 20th	Night	14% 7% 21% 41% 14% 2	760
	21st to end	Night	10% 5% 24% 42% 17% 2	630
May	1st to 10th	Night	11% 5% 21% 43% 18% 1	630
	11th to 20th	Night	10% 4 19% 35% 28% 4	550
	21st to end	Night	11% 3 14% 38% 30% 4	455
June	1st to 10th	Night	11% 3 15% 40% 29% 3	420
	11th to 20th	Night	10% 4 17% 46% 22% 2	420
	21st to end	Night	4 1 13% 51% 29% 3	420
July	1st to 10th	Night	3 1 13% 49% 32% 2	410
	11th to 20th	Night	2 1 12% 58% 26% 1	408
	21st to end	Night	3 11% 50% 34% 2	460
August	1st to 10th	Night	4 1 10% 50% 31% 3	548
	11th to 20th	Night	2 2 13% 47% 33% 3	624
	21st to end	Night	4 2 13% 47% 31% 4	871
September	1st to 10th	Night	4 2 9% 49% 32% 4	840
	11th to 20th	Night	7% 2 11% 40% 34% 6%	840
	21st to end	Night	9% 2 13% 40% 30% 7%	832
October	1st to 10th	Night	10% 3 12% 42% 29% 4	800
	11th to 20th	Night	11% 4 15% 40% 26% 4	800
	21st to end	Night	14% 3 17% 41% 21% 4	880
November	1st to 10th	Night	18% 4 16% 40% 21% 2	820
	11th to 20th	Night	21% 3 20% 37% 17% 2	840
	21st to end	Night	17% 4 19% 38% 18% 4	840
December	1st to 10th	Night	20% 5% 15% 39% 19% 2	840
	11th to 20th	Night	23% 5% 18% 36% 15% 3	840
	21st to end	Night	27% 6% 20% 34% 11% 2	924

Page generated at 2026-09-26 02:18:43. Version ac07

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