Fort Steele Resort & RV Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Steele Resort & RV Park clear sky chart from 2005-11-06 to 2026-03-03.

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 9% 6% 6% 6% 5% 7% 8% 38%	134770
	Night	5% 11% 4 10% 6% 5% 5% 5% 7% 8% 34%	135087
Transparency	Day	40% 10% 18% 20% 10% 2	134487
	Night	42% 12% 19% 18% 8% 1	134949
Seeing	Day	15% 10% 25% 29% 17% 4	16768
	Night	13% 6% 22% 38% 19% 2	26042

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	4 14% 9% 19% 10% 9% 7% 4 6% 6% 11%	4125
	11th to 20th	Day	3 10% 3 10% 6% 6% 7% 5% 8% 10% 33%	4715
	21st to end	Day	4 9% 4 10% 7% 7% 7% 6% 8% 9% 30%	5186
February	1st to 10th	Day	4 11% 5% 12% 9% 7% 7% 6% 9% 8% 22%	1680
	11th to 20th	Day	2 12% 5% 14% 7% 6% 6% 6% 10% 7% 24%	1866
	21st to end	Day	3 12% 4 12% 9% 8% 7% 5% 8% 7% 24%	1730
March	1st to 10th	Day	3 11% 4 10% 6% 6% 6% 5% 8% 9% 31%	4539
	11th to 20th	Day	2 10% 4 12% 8% 7% 6% 5% 7% 6% 33%	4820
	21st to end	Day	6% 14% 5% 13% 8% 7% 6% 4 7% 9% 21%	5736
April	1st to 10th	Day	6% 13% 6% 10% 7% 6% 7% 5% 6% 8% 27%	2400
	11th to 20th	Day	6% 12% 5% 10% 7% 6% 5% 5% 6% 8% 31%	2543
	21st to end	Day	8% 12% 4 9% 7% 6% 6% 4 6% 7% 31%	2600
May	1st to 10th	Day	10% 10% 4 9% 5% 6% 5% 4 6% 6% 37%	6144
	11th to 20th	Day	8% 10% 3 12% 7% 7% 6% 6% 7% 9% 25%	6459
	21st to end	Day	8% 8% 3 8% 5% 5% 5% 5% 7% 8% 37%	7405
June	1st to 10th	Day	12% 10% 3 8% 7% 5% 6% 5% 6% 6% 32%	3000
	11th to 20th	Day	10% 10% 3 9% 7% 7% 6% 6% 8% 8% 27%	3000
	21st to end	Day	6% 5% 2 6% 6% 5% 6% 5% 7% 8% 43%	3000
July	1st to 10th	Day	4 3 2 4 3 4 4 4 6% 7% 60%	6780
	11th to 20th	Day	4 2 1 4 3 3 4 4 6% 7% 63%	6656
	21st to end	Day	4 2 1 4 3 3 4 4 6% 9% 60%	6874
August	1st to 10th	Day	3 3 1 4 3 4 5% 5% 7% 10% 53%	4541
	11th to 20th	Day	5% 3 1 3 3 4 4 4 7% 8% 58%	4248
	21st to end	Day	5% 3 2 6% 4 4 5% 4 6% 8% 54%	4633
September	1st to 10th	Day	5% 4 2 4 4 4 4 4 6% 8% 55%	2400
	11th to 20th	Day	7% 6% 3 6% 4 4 5% 4 5% 8% 48%	2233
	21st to end	Day	8% 6% 2 7% 4 5% 5% 4 6% 9% 45%	2200
October	1st to 10th	Day	5% 4 1 5% 4 4 5% 5% 7% 9% 49%	3555
	11th to 20th	Day	6% 6% 2 8% 5% 5% 6% 5% 7% 9% 42%	2932
	21st to end	Day	9% 11% 5% 9% 5% 5% 5% 4 5% 7% 36%	3200
November	1st to 10th	Day	9% 13% 5% 11% 7% 7% 7% 5% 7% 7% 23%	1854
	11th to 20th	Day	8% 10% 5% 11% 7% 7% 6% 5% 7% 7% 25%	1599
	21st to end	Day	4 13% 4 12% 7% 8% 8% 7% 8% 8% 20%	1470
December	1st to 10th	Day	4 10% 3 14% 8% 7% 7% 6% 9% 9% 24%	2360
	11th to 20th	Day	7% 17% 8% 16% 10% 8% 6% 4 6% 5% 14%	2712
	21st to end	Day	5% 17% 6% 15% 10% 10% 7% 4 4 5% 15%	3575
January	1st to 10th	Night	5% 22% 9% 15% 8% 7% 6% 5% 7% 6% 11%	8768
	11th to 20th	Night	4 9% 4 10% 6% 6% 7% 6% 9% 9% 29%	8228
	21st to end	Night	5% 13% 4 11% 6% 5% 6% 4 8% 10% 27%	8994
February	1st to 10th	Night	5% 14% 6% 13% 8% 7% 6% 5% 6% 8% 21%	2940
	11th to 20th	Night	3 13% 5% 12% 7% 6% 6% 5% 6% 8% 28%	2639
	21st to end	Night	4 15% 5% 10% 7% 6% 6% 6% 7% 7% 27%	2076
March	1st to 10th	Night	2 10% 6% 12% 6% 6% 6% 5% 7% 7% 34%	5400
	11th to 20th	Night	3 12% 5% 12% 7% 6% 6% 6% 6% 8% 31%	5178
	21st to end	Night	7% 14% 5% 11% 7% 7% 6% 5% 7% 8% 23%	5236
April	1st to 10th	Night	6% 10% 3 7% 5% 5% 5% 6% 7% 9% 37%	2000
	11th to 20th	Night	5% 11% 4 10% 5% 5% 6% 5% 6% 8% 37%	1807
	21st to end	Night	6% 11% 3 7% 6% 5% 5% 5% 6% 7% 38%	1800
May	1st to 10th	Night	8% 10% 3 8% 5% 5% 5% 4 6% 6% 40%	3807
	11th to 20th	Night	8% 8% 3 9% 6% 6% 6% 5% 8% 10% 32%	3418
	21st to end	Night	7% 8% 3 7% 4 3 4 4 6% 9% 44%	3470
June	1st to 10th	Night	10% 7% 4 8% 5% 5% 4 5% 6% 8% 39%	1400
	11th to 20th	Night	11% 7% 2 8% 6% 6% 6% 5% 8% 7% 35%	1400
	21st to end	Night	4 6% 2 7% 4 4 4 4 8% 9% 49%	1400
July	1st to 10th	Night	4 3 1 3 3 3 4 4 6% 7% 63%	3180
	11th to 20th	Night	4 3 1 4 3 3 3 3 5% 7% 63%	3288
	21st to end	Night	4 2 1 3 2 3 3 3 5% 6% 69%	3969
August	1st to 10th	Night	3 4 1 4 2 3 4 4 6% 9% 60%	2609
	11th to 20th	Night	3 3 1 4 3 4 4 4 6% 10% 57%	2807
	21st to end	Night	4 3 1 4 3 3 4 4 7% 9% 58%	3273
September	1st to 10th	Night	3 4 2 3 3 3 3 3 6% 7% 62%	2000
	11th to 20th	Night	6% 6% 2 4 3 4 5% 4 5% 8% 53%	2166
	21st to end	Night	6% 6% 2 6% 3 3 5% 3 5% 8% 52%	2200
October	1st to 10th	Night	4 4 1 5% 4 5% 4 4 7% 9% 53%	3643
	11th to 20th	Night	7% 6% 2 7% 4 3 4 4 5% 8% 50%	4216
	21st to end	Night	7% 8% 3 9% 6% 5% 5% 5% 5% 7% 40%	4600
November	1st to 10th	Night	8% 13% 5% 10% 7% 6% 6% 5% 7% 8% 26%	2665
	11th to 20th	Night	7% 14% 5% 11% 7% 6% 5% 5% 8% 8% 24%	2997
	21st to end	Night	5% 17% 7% 13% 8% 7% 6% 5% 6% 7% 20%	3150
December	1st to 10th	Night	5% 11% 4 13% 7% 6% 8% 7% 11% 8% 21%	5040
	11th to 20th	Night	6% 18% 7% 18% 9% 8% 7% 4 5% 5% 12%	5700
	21st to end	Night	4 17% 7% 17% 10% 9% 7% 4 5% 6% 13%	7623

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% 13% 16% 7% 2	4125
	11th to 20th	Day	41% 16% 23% 14% 3 2	4739
	21st to end	Day	45% 19% 20% 12% 4	5187
February	1st to 10th	Day	52% 14% 17% 8% 8% 1	1680
	11th to 20th	Day	52% 14% 17% 12% 5%	1875
	21st to end	Day	51% 12% 19% 12% 7%	1730
March	1st to 10th	Day	40% 10% 21% 20% 9%	4539
	11th to 20th	Day	40% 10% 28% 16% 6%	4821
	21st to end	Day	52% 14% 17% 12% 5%	5736
April	1st to 10th	Day	51% 10% 20% 15% 3	2400
	11th to 20th	Day	49% 8% 18% 19% 5% 1	2543
	21st to end	Day	50% 9% 15% 19% 6% 1	2600
May	1st to 10th	Day	44% 6% 14% 23% 13% 1	6144
	11th to 20th	Day	48% 10% 17% 21% 4	6463
	21st to end	Day	38% 10% 22% 23% 7%	7406
June	1st to 10th	Day	49% 8% 13% 18% 10% 1	3000
	11th to 20th	Day	49% 10% 15% 17% 7% 1	3000
	21st to end	Day	34% 11% 17% 24% 13% 2	3000
July	1st to 10th	Day	22% 6% 14% 26% 27% 6%	6706
	11th to 20th	Day	19% 6% 15% 24% 27% 9%	6575
	21st to end	Day	21% 5% 16% 28% 18% 12%	6681
August	1st to 10th	Day	22% 8% 20% 27% 18% 5%	4524
	11th to 20th	Day	21% 8% 22% 33% 14% 2	4289
	21st to end	Day	25% 7% 22% 32% 14% 1	4632
September	1st to 10th	Day	26% 7% 16% 32% 17% 3	2400
	11th to 20th	Day	34% 8% 17% 29% 12% 1	2233
	21st to end	Day	34% 10% 21% 24% 9% 1	2200
October	1st to 10th	Day	28% 9% 24% 35% 5%	3555
	11th to 20th	Day	33% 12% 22% 25% 7%	2932
	21st to end	Day	44% 10% 20% 19% 7%	3200
November	1st to 10th	Day	57% 12% 16% 12% 3	1854
	11th to 20th	Day	53% 13% 18% 11% 5%	1599
	21st to end	Day	53% 18% 20% 7% 2	1470
December	1st to 10th	Day	51% 19% 18% 11% 1	2360
	11th to 20th	Day	67% 12% 14% 6% 1	2714
	21st to end	Day	64% 9% 16% 7% 3 1	3575
January	1st to 10th	Night	61% 15% 15% 6% 2	8769
	11th to 20th	Night	43% 18% 19% 12% 6% 2	8266
	21st to end	Night	46% 18% 19% 15% 2	8994
February	1st to 10th	Night	56% 11% 16% 10% 7%	2940
	11th to 20th	Night	50% 11% 19% 14% 7%	2640
	21st to end	Night	47% 11% 20% 15% 7%	2076
March	1st to 10th	Night	38% 9% 29% 16% 8%	5400
	11th to 20th	Night	41% 9% 28% 18% 4	5178
	21st to end	Night	47% 16% 20% 14% 3	5236
April	1st to 10th	Night	38% 13% 26% 16% 7%	2000
	11th to 20th	Night	41% 9% 20% 23% 7%	1807
	21st to end	Night	42% 9% 16% 26% 7% 1	1800
May	1st to 10th	Night	39% 8% 16% 24% 13% 1	3804
	11th to 20th	Night	39% 9% 21% 23% 8%	3418
	21st to end	Night	34% 8% 23% 28% 8%	3470
June	1st to 10th	Night	41% 9% 18% 22% 8% 2	1400
	11th to 20th	Night	42% 10% 17% 21% 9% 2	1400
	21st to end	Night	29% 9% 19% 27% 14% 2	1400
July	1st to 10th	Night	18% 7% 19% 26% 23% 7%	3145
	11th to 20th	Night	20% 6% 16% 22% 26% 11%	3246
	21st to end	Night	16% 5% 19% 28% 19% 13%	3857
August	1st to 10th	Night	19% 6% 20% 30% 19% 5%	2601
	11th to 20th	Night	21% 7% 26% 28% 16% 2	2832
	21st to end	Night	18% 7% 25% 33% 16% 2	3273
September	1st to 10th	Night	21% 7% 16% 34% 18% 5%	2000
	11th to 20th	Night	28% 8% 18% 31% 13% 2	2166
	21st to end	Night	27% 9% 22% 27% 13% 1	2200
October	1st to 10th	Night	23% 8% 26% 34% 9%	3643
	11th to 20th	Night	29% 9% 22% 32% 7% 1	4216
	21st to end	Night	36% 12% 24% 25% 3	4600
November	1st to 10th	Night	50% 14% 18% 14% 4 1	2665
	11th to 20th	Night	52% 12% 18% 12% 6%	2997
	21st to end	Night	59% 12% 17% 9% 3	3150
December	1st to 10th	Night	50% 23% 15% 10% 2	5040
	11th to 20th	Night	68% 12% 12% 7% 1	5697
	21st to end	Night	63% 12% 14% 7% 3	7623

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	18% 6% 15% 35% 17% 8%	220
	11th to 20th	Day	13% 3 22% 38% 17% 7%	220
	21st to end	Day	8% 4 25% 40% 16% 7%	242
February	1st to 10th	Day	10% 5% 37% 34% 12% 3	220
	11th to 20th	Day	11% 8% 26% 35% 18% 2	373
	21st to end	Day	14% 12% 26% 28% 17% 3	446
March	1st to 10th	Day	13% 13% 31% 24% 13% 5%	509
	11th to 20th	Day	16% 12% 26% 21% 19% 6%	500
	21st to end	Day	19% 14% 26% 25% 11% 5%	550
April	1st to 10th	Day	21% 13% 24% 25% 14% 3	500
	11th to 20th	Day	18% 14% 27% 22% 14% 5%	492
	21st to end	Day	18% 13% 24% 23% 16% 6%	500
May	1st to 10th	Day	18% 10% 25% 27% 16% 4	503
	11th to 20th	Day	19% 10% 22% 27% 19% 3	606
	21st to end	Day	19% 8% 18% 29% 22% 4	789
June	1st to 10th	Day	21% 11% 25% 27% 13% 2	730
	11th to 20th	Day	18% 13% 26% 26% 16% 2	730
	21st to end	Day	11% 10% 25% 30% 21% 5%	730
July	1st to 10th	Day	8% 8% 23% 34% 23% 4	721
	11th to 20th	Day	7% 10% 25% 34% 21% 3	672
	21st to end	Day	6% 12% 29% 32% 17% 4	575
August	1st to 10th	Day	5% 7% 26% 37% 20% 5%	527
	11th to 20th	Day	7% 6% 27% 31% 23% 6%	517
	21st to end	Day	11% 8% 24% 31% 20% 6%	583
September	1st to 10th	Day	9% 9% 25% 29% 19% 8%	530
	11th to 20th	Day	13% 11% 20% 28% 20% 9%	530
	21st to end	Day	18% 13% 27% 24% 16% 2	530
October	1st to 10th	Day	13% 11% 25% 29% 16% 5%	520
	11th to 20th	Day	17% 8% 29% 22% 18% 5%	330
	21st to end	Day	24% 9% 26% 27% 11% 3	363
November	1st to 10th	Day	23% 9% 22% 33% 12% 1	330
	11th to 20th	Day	24% 11% 23% 31% 8% 3	278
	21st to end	Day	14% 9% 18% 35% 19% 5%	220
December	1st to 10th	Day	16% 4 21% 33% 18% 8%	220
	11th to 20th	Day	18% 9% 17% 37% 13% 6%	220
	21st to end	Day	15% 6% 17% 38% 21% 3	242
January	1st to 10th	Night	18% 8% 25% 33% 13% 3	1050
	11th to 20th	Night	14% 5% 25% 40% 13% 3	860
	21st to end	Night	14% 3 25% 42% 13% 4	924
February	1st to 10th	Night	14% 7% 24% 40% 13% 3	840
	11th to 20th	Night	11% 5% 25% 39% 18% 2	824
	21st to end	Night	13% 6% 22% 36% 18% 4	692
March	1st to 10th	Night	12% 7% 26% 36% 17% 2	808
	11th to 20th	Night	15% 8% 24% 33% 18% 2	800
	21st to end	Night	14% 6% 26% 36% 16% 3	880
April	1st to 10th	Night	13% 6% 25% 35% 21% 1	800
	11th to 20th	Night	11% 8% 30% 37% 15%	619
	21st to end	Night	13% 6% 27% 36% 17% 1	600
May	1st to 10th	Night	12% 7% 21% 37% 22% 1	476
	11th to 20th	Night	11% 4 15% 39% 28% 3	394
	21st to end	Night	19% 3 15% 34% 27% 2	433
June	1st to 10th	Night	17% 4 22% 35% 20% 3	400
	11th to 20th	Night	15% 5% 19% 39% 21% 1	400
	21st to end	Night	9% 4 19% 43% 24% 3	400
July	1st to 10th	Night	5% 1 15% 45% 32% 2	390
	11th to 20th	Night	5% 2 19% 51% 21% 2	388
	21st to end	Night	3 2 17% 45% 31% 1	438
August	1st to 10th	Night	5% 2 11% 46% 34% 3	398
	11th to 20th	Night	6% 3 13% 40% 36% 2	536
	21st to end	Night	7% 4 17% 45% 25% 2	675
September	1st to 10th	Night	6% 2 18% 44% 25% 5%	800
	11th to 20th	Night	10% 3 15% 36% 32% 4	800
	21st to end	Night	11% 5% 22% 38% 20% 4	800
October	1st to 10th	Night	13% 3 23% 40% 20% 1	800
	11th to 20th	Night	15% 3 24% 38% 19% 2	800
	21st to end	Night	18% 6% 24% 37% 13% 2	880
November	1st to 10th	Night	17% 8% 24% 39% 12% 1	820
	11th to 20th	Night	18% 10% 25% 31% 14% 2	1012
	21st to end	Night	14% 10% 23% 35% 16% 2	1050
December	1st to 10th	Night	16% 5% 22% 39% 16% 3	1050
	11th to 20th	Night	16% 7% 22% 40% 14% 1	1050
	21st to end	Night	16% 7% 20% 40% 15% 2	1155

Page generated at 2026-02-27 22:40:24. Version ac07

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