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 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	7% 9% 3 6% 4 4 4 3 5% 6% 49%	101297
	Night	8% 10% 3 6% 4 4 4 3 5% 6% 47%	97844
Transparency	Day	35% 5% 8% 19% 20% 13%	101041
	Night	37% 5% 10% 21% 18% 10%	97690
Seeing	Day	15% 11% 29% 28% 14% 4	14427
	Night	15% 3 15% 41% 24% 3	23737

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% 21% 9% 11% 5% 5% 4 4 5% 6% 23%	2539
	11th to 20th	Day	10% 20% 10% 10% 5% 4 3 2 4 5% 27%	2540
	21st to end	Day	13% 19% 5% 8% 5% 5% 4 3 4 7% 26%	2794
February	1st to 10th	Day	11% 19% 6% 10% 6% 3 3 3 4 5% 30%	1666
	11th to 20th	Day	10% 22% 5% 8% 5% 5% 4 3 4 6% 28%	1850
	21st to end	Day	8% 21% 8% 10% 7% 5% 4 4 5% 5% 23%	1570
March	1st to 10th	Day	7% 16% 7% 12% 5% 5% 4 3 5% 6% 27%	3138
	11th to 20th	Day	7% 12% 3 6% 4 3 3 3 4 5% 51%	3384
	21st to end	Day	10% 16% 5% 11% 7% 7% 6% 5% 6% 7% 20%	3966
April	1st to 10th	Day	11% 15% 5% 8% 5% 4 3 4 5% 7% 32%	2280
	11th to 20th	Day	9% 13% 3 7% 5% 4 5% 3 5% 6% 38%	2313
	21st to end	Day	10% 12% 3 7% 5% 4 5% 3 5% 6% 40%	2470
May	1st to 10th	Day	7% 13% 4 8% 6% 5% 5% 4 5% 5% 38%	4110
	11th to 20th	Day	6% 5% 1 5% 4 3 4 3 4 6% 59%	4179
	21st to end	Day	7% 7% 3 6% 5% 5% 5% 4 5% 6% 46%	4813
June	1st to 10th	Day	12% 7% 3 7% 5% 4 5% 4 6% 7% 40%	2660
	11th to 20th	Day	9% 6% 2 4 4 4 4 3 5% 7% 51%	2660
	21st to end	Day	3 3 1 3 3 2 3 3 4 5% 68%	2660
July	1st to 10th	Day	2 1 1 1 1 1 2 2 3 4 81%	4420
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 5% 77%	4420
	21st to end	Day	2 2 1 3 2 3 2 2 4 5% 72%	4790
August	1st to 10th	Day	3 3 2 5% 4 4 4 4 5% 7% 60%	4198
	11th to 20th	Day	1 2 1 3 2 2 2 2 4 5% 76%	4028
	21st to end	Day	2 3 1 4 3 2 2 2 3 4 73%	4249
September	1st to 10th	Day	4 2 1 3 2 2 2 2 4 6% 72%	2280
	11th to 20th	Day	7% 5% 2 5% 3 3 3 3 4 6% 59%	2090
	21st to end	Day	7% 5% 2 4 2 2 3 2 5% 6% 62%	2090
October	1st to 10th	Day	9% 7% 2 6% 4 4 3 3 4 6% 51%	2090
	11th to 20th	Day	9% 7% 2 5% 4 3 3 3 4 7% 52%	1838
	21st to end	Day	10% 10% 3 8% 4 5% 3 4 5% 6% 43%	1881
November	1st to 10th	Day	14% 13% 3 7% 4 3 4 3 6% 7% 36%	1683
	11th to 20th	Day	15% 13% 3 6% 5% 4 5% 4 5% 6% 34%	1710
	21st to end	Day	11% 13% 3 8% 4 5% 4 4 4 7% 37%	1696
December	1st to 10th	Day	16% 16% 4 7% 4 3 4 3 4 6% 33%	1520
	11th to 20th	Day	12% 16% 5% 11% 5% 5% 3 3 7% 7% 26%	1928
	21st to end	Day	11% 12% 5% 9% 5% 4 4 3 5% 6% 34%	2794
January	1st to 10th	Night	10% 19% 6% 9% 5% 5% 5% 4 4 6% 27%	4406
	11th to 20th	Night	13% 21% 8% 10% 4 4 4 3 4 5% 25%	4420
	21st to end	Night	13% 18% 5% 9% 5% 5% 4 4 5% 7% 26%	4862
February	1st to 10th	Night	12% 18% 4 8% 5% 4 3 3 4 6% 32%	2509
	11th to 20th	Night	11% 16% 4 7% 4 3 4 4 5% 7% 36%	2218
	21st to end	Night	10% 17% 6% 11% 6% 4 5% 3 5% 5% 29%	1884
March	1st to 10th	Night	9% 16% 5% 8% 5% 4 4 3 4 8% 34%	3736
	11th to 20th	Night	8% 12% 3 6% 3 3 3 3 4 5% 51%	3595
	21st to end	Night	7% 12% 3 8% 5% 6% 6% 5% 8% 9% 31%	3684
April	1st to 10th	Night	11% 11% 3 7% 5% 4 4 4 5% 6% 41%	1900
	11th to 20th	Night	10% 9% 3 6% 4 5% 5% 3 5% 5% 45%	1815
	21st to end	Night	7% 6% 3 6% 4 4 4 3 5% 7% 50%	1710
May	1st to 10th	Night	8% 10% 2 5% 3 4 4 4 6% 8% 47%	2860
	11th to 20th	Night	5% 3 1 4 3 3 4 4 4 6% 62%	2717
	21st to end	Night	6% 6% 2 6% 4 4 4 3 5% 7% 53%	2762
June	1st to 10th	Night	11% 4 2 5% 5% 4 5% 3 7% 9% 45%	1520
	11th to 20th	Night	8% 6% 2 4 3 2 4 3 5% 6% 58%	1520
	21st to end	Night	3 3 1 3 3 4 4 4 5% 5% 66%	1520
July	1st to 10th	Night	1 1 2 2 2 3 2 3 4 81%	2540
	11th to 20th	Night	1 1 1 2 2 3 2 3 4 4 77%	2540
	21st to end	Night	2 2 1 4 3 3 3 3 5% 6% 68%	2761
August	1st to 10th	Night	3 4 1 5% 4 4 4 3 5% 7% 60%	2738
	11th to 20th	Night	1 2 2 2 2 3 2 4 5% 76%	2811
	21st to end	Night	2 3 1 3 2 2 2 2 3 4 75%	3424
September	1st to 10th	Night	2 2 1 3 2 2 2 2 3 5% 74%	1900
	11th to 20th	Night	7% 3 2 4 3 3 4 3 5% 5% 62%	2089
	21st to end	Night	7% 3 2 3 2 2 2 3 4 5% 67%	2090
October	1st to 10th	Night	8% 4 2 4 3 2 4 3 5% 7% 58%	2090
	11th to 20th	Night	9% 5% 2 4 3 4 3 3 5% 7% 55%	2339
	21st to end	Night	10% 8% 2 6% 3 4 4 4 6% 7% 46%	2717
November	1st to 10th	Night	14% 10% 2 6% 4 4 5% 2 6% 7% 40%	2418
	11th to 20th	Night	16% 11% 2 6% 5% 5% 4 4 5% 6% 37%	2470
	21st to end	Night	11% 12% 3 6% 4 4 4 3 4 7% 41%	2481
December	1st to 10th	Night	12% 14% 4 7% 4 5% 4 4 6% 7% 33%	2660
	11th to 20th	Night	11% 16% 4 10% 6% 5% 5% 4 6% 6% 27%	3276
	21st to end	Night	11% 13% 5% 9% 5% 4 4 3 5% 7% 34%	4862

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	61% 7% 12% 17% 2 1	2539
	11th to 20th	Day	60% 5% 10% 17% 7%	2540
	21st to end	Day	58% 5% 17% 15% 4 1	2794
February	1st to 10th	Day	56% 5% 14% 19% 5% 1	1666
	11th to 20th	Day	56% 6% 12% 17% 8%	1860
	21st to end	Day	59% 7% 9% 16% 9% 1	1570
March	1st to 10th	Day	55% 6% 8% 18% 13%	3138
	11th to 20th	Day	34% 5% 7% 34% 18% 1	3384
	21st to end	Day	56% 10% 11% 16% 7% 1	3966
April	1st to 10th	Day	51% 5% 13% 18% 11% 2	2280
	11th to 20th	Day	46% 4 10% 23% 16% 2	2316
	21st to end	Day	43% 6% 10% 25% 16%	2470
May	1st to 10th	Day	44% 6% 7% 22% 18% 3	4110
	11th to 20th	Day	25% 5% 5% 29% 26% 10%	4182
	21st to end	Day	34% 7% 9% 34% 15% 3	4814
June	1st to 10th	Day	40% 7% 10% 27% 16% 1	2660
	11th to 20th	Day	32% 4 5% 23% 27% 9%	2660
	21st to end	Day	18% 4 4 19% 37% 18%	2660
July	1st to 10th	Day	9% 2 2 11% 20% 57%	4351
	11th to 20th	Day	11% 2 2 6% 22% 57%	4345
	21st to end	Day	13% 3 2 9% 34% 39%	4639
August	1st to 10th	Day	22% 5% 4 10% 29% 30%	4182
	11th to 20th	Day	11% 3 2 13% 44% 28%	4067
	21st to end	Day	16% 2 2 18% 34% 28%	4248
September	1st to 10th	Day	15% 3 4 17% 33% 29%	2280
	11th to 20th	Day	26% 4 6% 23% 27% 14%	2090
	21st to end	Day	23% 3 4 27% 31% 11%	2090
October	1st to 10th	Day	34% 4 8% 22% 24% 7%	2090
	11th to 20th	Day	32% 3 10% 30% 21% 4	1838
	21st to end	Day	40% 6% 12% 23% 18% 2	1881
November	1st to 10th	Day	47% 5% 12% 20% 16% 1	1683
	11th to 20th	Day	48% 6% 16% 21% 8%	1710
	21st to end	Day	46% 5% 13% 23% 11% 2	1696
December	1st to 10th	Day	51% 5% 18% 17% 8% 1	1520
	11th to 20th	Day	56% 6% 18% 15% 5%	1928
	21st to end	Day	49% 5% 12% 22% 10% 1	2794
January	1st to 10th	Night	56% 7% 15% 19% 3 1	4406
	11th to 20th	Night	62% 6% 10% 15% 7%	4420
	21st to end	Night	55% 9% 12% 19% 5%	4862
February	1st to 10th	Night	52% 6% 15% 21% 5% 1	2509
	11th to 20th	Night	47% 6% 15% 21% 11% 1	2219
	21st to end	Night	55% 6% 9% 18% 11% 1	1884
March	1st to 10th	Night	47% 6% 9% 20% 16% 1	3736
	11th to 20th	Night	36% 4 8% 31% 19% 2	3595
	21st to end	Night	43% 10% 16% 23% 8%	3684
April	1st to 10th	Night	42% 5% 11% 25% 14% 2	1900
	11th to 20th	Night	39% 5% 10% 26% 18% 2	1815
	21st to end	Night	33% 4 13% 30% 19% 1	1710
May	1st to 10th	Night	33% 6% 8% 29% 21% 4	2860
	11th to 20th	Night	21% 5% 7% 32% 31% 4	2718
	21st to end	Night	29% 5% 11% 36% 18% 1	2762
June	1st to 10th	Night	35% 5% 13% 30% 16% 1	1520
	11th to 20th	Night	26% 5% 7% 25% 30% 8%	1520
	21st to end	Night	18% 4 5% 19% 35% 18%	1520
July	1st to 10th	Night	9% 2 2 9% 22% 56%	2500
	11th to 20th	Night	10% 3 2 8% 19% 57%	2492
	21st to end	Night	17% 4 2 8% 31% 38%	2674
August	1st to 10th	Night	22% 4 4 9% 27% 34%	2730
	11th to 20th	Night	11% 3 2 11% 38% 36%	2838
	21st to end	Night	15% 3 2 17% 31% 32%	3424
September	1st to 10th	Night	15% 2 4 15% 34% 31%	1900
	11th to 20th	Night	24% 3 6% 19% 28% 19%	2089
	21st to end	Night	22% 2 3 26% 31% 16%	2090
October	1st to 10th	Night	26% 3 8% 27% 26% 10%	2090
	11th to 20th	Night	29% 4 10% 29% 23% 5%	2339
	21st to end	Night	35% 6% 12% 25% 19% 3	2717
November	1st to 10th	Night	42% 5% 12% 21% 19% 2	2418
	11th to 20th	Night	47% 6% 12% 25% 10%	2470
	21st to end	Night	44% 4 12% 24% 13% 3	2481
December	1st to 10th	Night	48% 7% 16% 18% 10% 1	2660
	11th to 20th	Night	55% 6% 14% 18% 6%	3276
	21st to end	Night	48% 6% 14% 21% 9% 1	4862

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	23% 8% 26% 22% 18% 4	180
	11th to 20th	Day	20% 8% 23% 24% 17% 8%	180
	21st to end	Day	15% 8% 25% 28% 17% 7%	198
February	1st to 10th	Day	27% 10% 23% 24% 12% 4	264
	11th to 20th	Day	21% 14% 31% 24% 8% 1	455
	21st to end	Day	22% 15% 28% 25% 8% 2	382
March	1st to 10th	Day	22% 15% 35% 22% 5% 1	460
	11th to 20th	Day	19% 13% 29% 23% 13% 3	460
	21st to end	Day	24% 16% 29% 23% 7% 1	506
April	1st to 10th	Day	23% 16% 27% 21% 12% 1	460
	11th to 20th	Day	19% 18% 33% 21% 8% 1	452
	21st to end	Day	19% 18% 32% 22% 8% 2	460
May	1st to 10th	Day	18% 13% 33% 24% 11% 2	463
	11th to 20th	Day	21% 14% 28% 25% 9% 4	488
	21st to end	Day	17% 7% 25% 29% 15% 6%	529
June	1st to 10th	Day	13% 12% 30% 25% 17% 3	490
	11th to 20th	Day	17% 14% 31% 26% 10% 2	490
	21st to end	Day	6% 10% 32% 32% 17% 2	490
July	1st to 10th	Day	5% 8% 34% 36% 14% 3	486
	11th to 20th	Day	2 10% 36% 34% 15% 3	484
	21st to end	Day	3 7% 33% 36% 16% 5%	531
August	1st to 10th	Day	5% 7% 33% 33% 17% 4	487
	11th to 20th	Day	3 10% 27% 33% 22% 6%	477
	21st to end	Day	5% 11% 28% 32% 20% 4	539
September	1st to 10th	Day	7% 9% 23% 37% 18% 6%	490
	11th to 20th	Day	9% 8% 29% 32% 19% 2	490
	21st to end	Day	8% 9% 32% 29% 18% 3	490
October	1st to 10th	Day	13% 10% 24% 29% 19% 6%	490
	11th to 20th	Day	12% 9% 28% 26% 17% 7%	361
	21st to end	Day	20% 9% 22% 30% 16% 3	330
November	1st to 10th	Day	22% 4 22% 34% 14% 3	273
	11th to 20th	Day	17% 8% 20% 35% 15% 5%	270
	21st to end	Day	17% 3 23% 33% 19% 5%	264
December	1st to 10th	Day	29% 5% 19% 21% 16% 10%	180
	11th to 20th	Day	24% 8% 23% 27% 13% 5%	180
	21st to end	Day	18% 7% 24% 34% 14% 4	198
January	1st to 10th	Night	24% 3 16% 34% 21% 3	760
	11th to 20th	Night	25% 4 16% 33% 20% 3	760
	21st to end	Night	20% 3 12% 40% 21% 4	836
February	1st to 10th	Night	23% 3 20% 37% 17% 2	760
	11th to 20th	Night	18% 4 18% 38% 19% 3	744
	21st to end	Night	20% 6% 16% 39% 17% 3	628
March	1st to 10th	Night	19% 5% 19% 39% 15% 2	760
	11th to 20th	Night	19% 4 16% 39% 21% 2	760
	21st to end	Night	20% 7% 17% 38% 17% 2	836
April	1st to 10th	Night	17% 6% 16% 38% 20% 3	760
	11th to 20th	Night	14% 6% 20% 41% 15% 3	687
	21st to end	Night	10% 5% 22% 42% 19% 2	570
May	1st to 10th	Night	12% 5% 21% 41% 20% 2	570
	11th to 20th	Night	10% 3 16% 35% 30% 5%	497
	21st to end	Night	12% 4 11% 37% 32% 4	411
June	1st to 10th	Night	12% 3 11% 40% 31% 3	380
	11th to 20th	Night	11% 4 14% 47% 23% 2	380
	21st to end	Night	3 1 11% 51% 32% 3	380
July	1st to 10th	Night	2 1 9% 51% 35% 2	370
	11th to 20th	Night	2 1 10% 58% 28% 1	368
	21st to end	Night	3 9% 49% 38% 2	416
August	1st to 10th	Night	5% 1 9% 47% 34% 4	496
	11th to 20th	Night	2 2 9% 48% 36% 3	564
	21st to end	Night	3 2 11% 47% 33% 4	788
September	1st to 10th	Night	4 2 7% 49% 34% 4	760
	11th to 20th	Night	8% 2 8% 39% 36% 6%	760
	21st to end	Night	9% 2 12% 38% 32% 8%	760
October	1st to 10th	Night	10% 3 10% 43% 31% 4	760
	11th to 20th	Night	11% 4 13% 40% 27% 4	760
	21st to end	Night	15% 2 16% 41% 22% 4	836
November	1st to 10th	Night	18% 3 13% 41% 22% 2	744
	11th to 20th	Night	21% 3 18% 38% 18% 2	760
	21st to end	Night	17% 3 16% 40% 18% 5%	760
December	1st to 10th	Night	20% 4 14% 41% 19% 2	760
	11th to 20th	Night	23% 4 15% 38% 16% 3	760
	21st to end	Night	27% 4 18% 36% 11% 3	836

Page generated at 2024-10-29 23:22:58. Version ac07

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