Loveland Pass
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Loveland Pass clear sky chart from 2005-11-06 to 2025-06-10.

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	3 9% 5% 12% 6% 5% 5% 4 5% 6% 41%	123631
	Night	1 6% 4 11% 6% 5% 5% 3 5% 7% 47%	123542
Transparency	Day	40% 5% 9% 20% 19% 7%	123380
	Night	30% 6% 13% 25% 20% 6%	123381
Seeing	Day	18% 22% 29% 20% 9% 2	16334
	Night	10% 16% 32% 30% 12% 1	26445

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	3 4 22% 12% 9% 3 2 3 5% 37%	3638
	11th to 20th	Day	6% 4 15% 11% 11% 8% 5% 3 4 33%	3893
	21st to end	Day	5% 6% 17% 5% 5% 5% 3 4 5% 45%	4510
February	1st to 10th	Day	8% 7% 17% 11% 5% 6% 3 5% 6% 33%	1800
	11th to 20th	Day	6% 7% 20% 8% 7% 3 3 3 5% 38%	1877
	21st to end	Day	6% 5% 20% 8% 7% 4 2 4 5% 38%	1650
March	1st to 10th	Day	5% 6% 22% 6% 4 3 2 3 4 45%	4585
	11th to 20th	Day	1 7% 8% 18% 8% 5% 4 3 5% 6% 35%	5000
	21st to end	Day	1 14% 11% 18% 6% 4 4 3 5% 5% 29%	5739
April	1st to 10th	Day	2 12% 6% 13% 6% 5% 4 3 5% 5% 39%	2400
	11th to 20th	Day	2 19% 8% 14% 6% 4 3 2 4 5% 32%	2371
	21st to end	Day	2 20% 7% 13% 6% 4 4 4 5% 5% 30%	2400
May	1st to 10th	Day	3 15% 10% 17% 7% 5% 5% 4 4 4 25%	5722
	11th to 20th	Day	3 15% 6% 11% 7% 5% 5% 4 5% 6% 33%	6298
	21st to end	Day	4 9% 3 8% 6% 5% 6% 5% 6% 8% 39%	6925
June	1st to 10th	Day	6% 8% 3 6% 4 5% 6% 4 7% 8% 42%	2788
	11th to 20th	Day	8% 8% 2 6% 5% 5% 4 3 6% 6% 47%	2660
	21st to end	Day	5% 6% 2 6% 6% 5% 5% 5% 6% 7% 46%	2660
July	1st to 10th	Day	6% 7% 2 6% 4 4 5% 4 5% 6% 50%	4430
	11th to 20th	Day	4 5% 2 8% 7% 7% 6% 6% 8% 9% 37%	4430
	21st to end	Day	8% 7% 3 9% 6% 6% 6% 5% 5% 6% 40%	4591
August	1st to 10th	Day	9% 8% 4 10% 8% 7% 7% 5% 7% 7% 30%	4092
	11th to 20th	Day	8% 7% 3 10% 6% 6% 5% 4 7% 6% 39%	3793
	21st to end	Day	8% 8% 3 10% 5% 5% 6% 4 6% 7% 37%	4180
September	1st to 10th	Day	8% 8% 3 8% 4 3 4 3 5% 5% 49%	2280
	11th to 20th	Day	8% 8% 3 7% 4 4 4 3 4 6% 50%	2280
	21st to end	Day	7% 9% 2 6% 3 3 4 3 4 5% 55%	2057
October	1st to 10th	Day	3 7% 2 4 2 3 2 2 4 5% 65%	3170
	11th to 20th	Day	3 10% 2 8% 6% 4 4 5% 6% 7% 45%	3150
	21st to end	Day	2 10% 3 9% 3 3 2 2 4 5% 55%	3407
November	1st to 10th	Day	1 8% 3 8% 4 4 4 3 5% 5% 54%	1763
	11th to 20th	Day	10% 4 7% 5% 3 3 2 5% 7% 53%	1800
	21st to end	Day	7% 4 12% 6% 3 2 3 4 6% 53%	1642
December	1st to 10th	Day	4 3 10% 9% 6% 4 2 3 6% 53%	2620
	11th to 20th	Day	6% 5% 13% 4 3 3 3 4 7% 52%	3026
	21st to end	Day	9% 5% 15% 8% 6% 5% 4 6% 8% 35%	4004
January	1st to 10th	Night	2 4 20% 13% 6% 4 3 4 5% 38%	6327
	11th to 20th	Night	3 4 16% 11% 9% 10% 3 4 4 38%	6128
	21st to end	Night	3 5% 15% 9% 7% 6% 3 4 4 44%	6468
February	1st to 10th	Night	6% 6% 15% 10% 7% 5% 3 5% 7% 36%	2600
	11th to 20th	Night	5% 5% 16% 10% 6% 5% 4 5% 6% 38%	2409
	21st to end	Night	5% 5% 16% 8% 7% 5% 3 4 5% 41%	1980
March	1st to 10th	Night	4 6% 22% 6% 5% 4 3 4 4 42%	5291
	11th to 20th	Night	5% 6% 15% 7% 4 3 3 4 7% 46%	5000
	21st to end	Night	1 15% 9% 17% 5% 4 4 3 5% 5% 31%	5224
April	1st to 10th	Night	8% 4 11% 6% 5% 4 4 6% 6% 46%	2000
	11th to 20th	Night	1 11% 5% 13% 6% 5% 4 3 4 7% 41%	1977
	21st to end	Night	2 13% 5% 10% 3 3 4 3 5% 7% 45%	2000
May	1st to 10th	Night	1 10% 5% 13% 5% 5% 6% 4 6% 8% 37%	4254
	11th to 20th	Night	2 12% 6% 7% 5% 4 5% 4 7% 8% 40%	3617
	21st to end	Night	2 9% 3 6% 4 4 4 3 5% 8% 52%	3972
June	1st to 10th	Night	3 4 1 5% 3 4 5% 4 7% 8% 54%	1596
	11th to 20th	Night	3 5% 1 3 4 4 3 4 4 7% 62%	1520
	21st to end	Night	3 5% 2 4 3 4 4 3 7% 9% 58%	1520
July	1st to 10th	Night	3 4 2 5% 4 3 4 3 6% 8% 57%	2540
	11th to 20th	Night	1 2 1 3 4 5% 6% 7% 9% 10% 51%	2540
	21st to end	Night	3 3 1 4 4 5% 6% 5% 8% 9% 53%	2968
August	1st to 10th	Night	4 5% 3 6% 4 5% 6% 6% 9% 10% 42%	2847
	11th to 20th	Night	4 3 2 5% 4 4 6% 5% 8% 9% 50%	3046
	21st to end	Night	3 4 2 6% 5% 6% 7% 5% 8% 8% 47%	3487
September	1st to 10th	Night	4 4 1 5% 4 4 4 4 7% 7% 57%	1900
	11th to 20th	Night	4 4 1 4 4 4 4 3 6% 6% 60%	1900
	21st to end	Night	4 5% 1 6% 4 3 4 3 5% 7% 60%	2118
October	1st to 10th	Night	2 4 1 3 2 2 3 2 4 5% 72%	3800
	11th to 20th	Night	1 5% 2 7% 4 4 4 4 6% 7% 58%	3778
	21st to end	Night	2 7% 3 7% 3 3 3 2 4 7% 61%	4120
November	1st to 10th	Night	5% 4 8% 4 3 3 3 4 7% 58%	2535
	11th to 20th	Night	6% 4 10% 5% 4 3 3 4 7% 54%	2600
	21st to end	Night	5% 5% 10% 6% 4 3 3 5% 8% 50%	2755
December	1st to 10th	Night	3 3 8% 6% 7% 4 3 3 4 60%	4570
	11th to 20th	Night	4 3 12% 7% 5% 4 4 5% 7% 50%	5181
	21st to end	Night	8% 6% 17% 7% 6% 5% 3 5% 7% 34%	6974

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	39% 7% 11% 20% 15% 8%	3639
	11th to 20th	Day	38% 9% 12% 16% 18% 7%	3893
	21st to end	Day	36% 6% 9% 19% 18% 12%	4510
February	1st to 10th	Day	39% 8% 17% 17% 14% 6%	1800
	11th to 20th	Day	37% 5% 13% 21% 18% 6%	1886
	21st to end	Day	38% 5% 10% 20% 19% 7%	1650
March	1st to 10th	Day	37% 4 6% 19% 24% 11%	4585
	11th to 20th	Day	46% 8% 7% 23% 14% 3	5000
	21st to end	Day	49% 3 12% 24% 11% 1	5739
April	1st to 10th	Day	40% 5% 12% 21% 16% 6%	2400
	11th to 20th	Day	49% 4 11% 18% 15% 3	2374
	21st to end	Day	50% 5% 10% 24% 10% 1	2400
May	1st to 10th	Day	54% 5% 6% 18% 14% 2	5722
	11th to 20th	Day	46% 6% 9% 22% 16% 1	6302
	21st to end	Day	38% 5% 8% 25% 21% 4	6926
June	1st to 10th	Day	37% 8% 12% 21% 17% 6%	2788
	11th to 20th	Day	36% 6% 8% 17% 22% 11%	2660
	21st to end	Day	35% 8% 7% 19% 21% 9%	2660
July	1st to 10th	Day	36% 5% 6% 11% 22% 20%	4361
	11th to 20th	Day	41% 6% 9% 19% 16% 8%	4355
	21st to end	Day	45% 6% 8% 13% 15% 14%	4446
August	1st to 10th	Day	53% 6% 11% 13% 13% 4	4078
	11th to 20th	Day	46% 5% 8% 12% 20% 8%	3830
	21st to end	Day	47% 5% 7% 14% 20% 7%	4179
September	1st to 10th	Day	37% 5% 7% 15% 26% 11%	2280
	11th to 20th	Day	36% 4 10% 17% 25% 8%	2280
	21st to end	Day	31% 5% 7% 24% 28% 6%	2057
October	1st to 10th	Day	21% 4 4 28% 35% 8%	3170
	11th to 20th	Day	37% 3 9% 28% 19% 4	3150
	21st to end	Day	31% 3 6% 30% 26% 4	3407
November	1st to 10th	Day	25% 5% 13% 22% 30% 6%	1763
	11th to 20th	Day	23% 5% 15% 27% 21% 8%	1800
	21st to end	Day	29% 5% 11% 26% 18% 10%	1642
December	1st to 10th	Day	27% 5% 10% 34% 18% 7%	2620
	11th to 20th	Day	25% 7% 16% 29% 21% 2	3024
	21st to end	Day	36% 6% 12% 17% 22% 6%	4004
January	1st to 10th	Night	37% 5% 12% 23% 15% 8%	6327
	11th to 20th	Night	34% 9% 12% 20% 16% 9%	6128
	21st to end	Night	28% 8% 12% 20% 20% 13%	6468
February	1st to 10th	Night	31% 8% 17% 21% 17% 5%	2600
	11th to 20th	Night	31% 5% 16% 24% 19% 5%	2410
	21st to end	Night	31% 5% 14% 21% 19% 9%	1980
March	1st to 10th	Night	35% 5% 8% 17% 25% 10%	5291
	11th to 20th	Night	32% 8% 9% 21% 26% 4	5000
	21st to end	Night	42% 5% 18% 25% 9% 1	5224
April	1st to 10th	Night	28% 7% 15% 25% 20% 5%	2000
	11th to 20th	Night	35% 7% 14% 26% 17% 3	1977
	21st to end	Night	33% 6% 15% 31% 15% 1	2000
May	1st to 10th	Night	37% 5% 11% 29% 16% 2	4251
	11th to 20th	Night	38% 8% 13% 25% 16%	3618
	21st to end	Night	26% 4 13% 32% 22% 2	3972
June	1st to 10th	Night	23% 7% 19% 30% 16% 6%	1596
	11th to 20th	Night	20% 6% 12% 23% 27% 12%	1520
	21st to end	Night	21% 6% 12% 24% 25% 11%	1520
July	1st to 10th	Night	26% 5% 9% 20% 22% 18%	2500
	11th to 20th	Night	26% 4 15% 31% 17% 6%	2492
	21st to end	Night	27% 6% 17% 24% 12% 14%	2875
August	1st to 10th	Night	36% 6% 21% 20% 14% 3	2838
	11th to 20th	Night	29% 7% 22% 16% 19% 7%	3075
	21st to end	Night	35% 7% 13% 20% 23% 3	3487
September	1st to 10th	Night	25% 6% 11% 22% 27% 8%	1900
	11th to 20th	Night	22% 6% 13% 25% 24% 10%	1900
	21st to end	Night	24% 6% 9% 30% 26% 5%	2118
October	1st to 10th	Night	14% 4 8% 32% 34% 8%	3800
	11th to 20th	Night	24% 3 10% 40% 18% 5%	3778
	21st to end	Night	22% 3 8% 31% 30% 6%	4120
November	1st to 10th	Night	20% 5% 14% 26% 28% 7%	2535
	11th to 20th	Night	22% 5% 14% 29% 23% 7%	2600
	21st to end	Night	26% 6% 11% 28% 21% 8%	2755
December	1st to 10th	Night	19% 5% 12% 35% 22% 6%	4570
	11th to 20th	Night	24% 7% 12% 30% 25% 2	5182
	21st to end	Night	41% 6% 11% 18% 19% 6%	6974

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% 25% 24% 20% 6% 2	300
	11th to 20th	Day	20% 32% 30% 13% 4 1	300
	21st to end	Day	15% 33% 32% 15% 4 1	330
February	1st to 10th	Day	30% 35% 24% 9% 1 1	300
	11th to 20th	Day	32% 31% 26% 9% 2	300
	21st to end	Day	31% 34% 23% 11% 1	249
March	1st to 10th	Day	25% 27% 28% 18% 3	333
	11th to 20th	Day	21% 27% 32% 16% 3 1	500
	21st to end	Day	20% 38% 29% 10% 2	550
April	1st to 10th	Day	23% 35% 28% 10% 3 1	500
	11th to 20th	Day	28% 35% 26% 8% 2 1	492
	21st to end	Day	21% 33% 35% 8% 3 1	500
May	1st to 10th	Day	19% 30% 30% 16% 4 1	568
	11th to 20th	Day	19% 18% 32% 22% 8% 1	725
	21st to end	Day	17% 20% 29% 22% 11% 2	789
June	1st to 10th	Day	12% 15% 29% 26% 15% 3	726
	11th to 20th	Day	15% 17% 32% 23% 10% 2	680
	21st to end	Day	8% 17% 32% 24% 16% 2	680
July	1st to 10th	Day	12% 8% 26% 30% 21% 4	671
	11th to 20th	Day	9% 9% 24% 32% 20% 6%	668
	21st to end	Day	12% 8% 26% 29% 20% 5%	616
August	1st to 10th	Day	18% 11% 30% 26% 13% 3	487
	11th to 20th	Day	13% 11% 30% 26% 15% 4	477
	21st to end	Day	14% 12% 31% 27% 12% 3	539
September	1st to 10th	Day	16% 13% 29% 25% 13% 5%	490
	11th to 20th	Day	14% 13% 38% 24% 10% 1	490
	21st to end	Day	14% 21% 25% 21% 15% 5%	314
October	1st to 10th	Day	11% 22% 27% 20% 16% 3	300
	11th to 20th	Day	17% 29% 25% 18% 8% 3	300
	21st to end	Day	24% 27% 25% 17% 5% 1	330
November	1st to 10th	Day	24% 29% 25% 14% 8%	300
	11th to 20th	Day	24% 27% 27% 16% 5% 1	300
	21st to end	Day	15% 27% 39% 17% 2	300
December	1st to 10th	Day	22% 27% 28% 16% 5% 1	300
	11th to 20th	Day	22% 30% 32% 12% 3 1	300
	21st to end	Day	25% 32% 27% 12% 5% 1	330
January	1st to 10th	Night	16% 23% 29% 23% 8% 1	1000
	11th to 20th	Night	17% 23% 32% 20% 6% 1	905
	21st to end	Night	9% 21% 43% 21% 6%	880
February	1st to 10th	Night	13% 26% 41% 15% 5%	800
	11th to 20th	Night	14% 25% 37% 20% 3	784
	21st to end	Night	11% 28% 41% 19% 2	660
March	1st to 10th	Night	10% 22% 39% 24% 5%	800
	11th to 20th	Night	7% 19% 37% 30% 6% 1	800
	21st to end	Night	8% 22% 45% 21% 4	770
April	1st to 10th	Night	10% 22% 42% 23% 2	600
	11th to 20th	Night	10% 23% 37% 24% 6% 1	593
	21st to end	Night	10% 17% 38% 27% 7% 1	600
May	1st to 10th	Night	10% 12% 40% 30% 8% 1	600
	11th to 20th	Night	11% 9% 30% 38% 12%	591
	21st to end	Night	10% 11% 29% 36% 14% 1	650
June	1st to 10th	Night	6% 7% 25% 42% 18% 1	599
	11th to 20th	Night	5% 11% 29% 43% 11% 1	570
	21st to end	Night	4 3 23% 46% 22% 1	570
July	1st to 10th	Night	7% 2 12% 44% 33% 2	555
	11th to 20th	Night	3 1 10% 48% 36% 3	552
	21st to end	Night	6% 1 12% 38% 39% 3	624
August	1st to 10th	Night	9% 2 13% 43% 31% 2	567
	11th to 20th	Night	6% 2 15% 48% 27% 2	564
	21st to end	Night	6% 2 13% 46% 29% 3	627
September	1st to 10th	Night	4 3 17% 48% 26% 3	570
	11th to 20th	Night	6% 4 23% 45% 20% 2	570
	21st to end	Night	6% 6% 29% 37% 19% 3	613
October	1st to 10th	Night	6% 11% 32% 34% 14% 2	760
	11th to 20th	Night	8% 19% 30% 30% 12% 1	760
	21st to end	Night	10% 16% 36% 28% 8% 2	836
November	1st to 10th	Night	7% 22% 38% 25% 8% 1	975
	11th to 20th	Night	13% 23% 38% 21% 4 1	1000
	21st to end	Night	9% 19% 39% 28% 5%	1000
December	1st to 10th	Night	10% 26% 38% 22% 4	1000
	11th to 20th	Night	13% 25% 37% 20% 5%	1000
	21st to end	Night	16% 23% 36% 20% 5% 1	1100

Page generated at 2025-06-07 08:28:19. Version ac07

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