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 2026-10-14.

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 8% 5% 12% 6% 6% 5% 4 5% 6% 40%	158224
	Night	1 6% 4 10% 6% 5% 5% 4 6% 7% 48%	151140
Transparency	Day	41% 5% 9% 20% 18% 7%	153159
	Night	30% 5% 13% 25% 20% 6%	147215
Seeing	Day	19% 22% 29% 19% 9% 2	18231
	Night	10% 16% 32% 29% 11% 1	28186

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	1 5% 6% 21% 10% 8% 3 2 3 4 37%	4720
	11th to 20th	Day	4 3 13% 10% 9% 7% 4 4 5% 40%	5077
	21st to end	Day	4 6% 16% 6% 6% 6% 3 4 5% 44%	5844
February	1st to 10th	Day	8% 7% 17% 10% 5% 6% 3 5% 6% 34%	1890
	11th to 20th	Day	6% 7% 20% 8% 7% 3 2 3 5% 38%	1973
	21st to end	Day	6% 5% 19% 8% 7% 4 2 4 5% 39%	1730
March	1st to 10th	Day	5% 5% 22% 6% 4 3 2 3 4 45%	4687
	11th to 20th	Day	1 7% 8% 17% 8% 5% 4 3 5% 6% 36%	5110
	21st to end	Day	1 14% 11% 18% 6% 4 4 3 5% 5% 30%	5865
April	1st to 10th	Day	2 12% 6% 13% 6% 5% 4 3 5% 5% 39%	2520
	11th to 20th	Day	2 18% 7% 14% 6% 4 3 2 4 6% 33%	2491
	21st to end	Day	2 19% 8% 13% 7% 4 4 3 4 5% 30%	2520
May	1st to 10th	Day	2 16% 9% 16% 7% 5% 5% 4 4 5% 27%	7417
	11th to 20th	Day	3 15% 5% 10% 7% 5% 5% 4 5% 6% 34%	8191
	21st to end	Day	3 10% 4 10% 7% 6% 7% 5% 6% 7% 35%	9026
June	1st to 10th	Day	5% 8% 3 6% 4 5% 6% 5% 7% 9% 42%	2940
	11th to 20th	Day	7% 7% 2 6% 5% 5% 4 3 6% 6% 49%	2940
	21st to end	Day	5% 6% 2 6% 6% 5% 6% 5% 6% 7% 47%	2940
July	1st to 10th	Day	5% 5% 2 7% 5% 6% 6% 5% 7% 8% 46%	8249
	11th to 20th	Day	4 5% 3 8% 7% 7% 7% 6% 8% 8% 38%	8250
	21st to end	Day	7% 7% 4 11% 7% 7% 6% 5% 6% 7% 34%	8564
August	1st to 10th	Day	5% 5% 3 7% 6% 6% 6% 5% 7% 9% 40%	7549
	11th to 20th	Day	6% 6% 3 9% 6% 7% 6% 5% 7% 7% 36%	7135
	21st to end	Day	8% 8% 4 11% 6% 6% 6% 5% 6% 8% 31%	7751
September	1st to 10th	Day	7% 8% 2 8% 4 4 5% 3 5% 5% 48%	2520
	11th to 20th	Day	8% 9% 3 8% 4 4 4 3 4 6% 47%	2520
	21st to end	Day	7% 10% 2 6% 3 3 4 3 4 5% 52%	2274
October	1st to 10th	Day	3 7% 2 4 3 3 3 2 4 5% 65%	3370
	11th to 20th	Day	3 10% 2 8% 6% 4 4 5% 6% 7% 46%	3280
	21st to end	Day	2 10% 3 9% 3 3 2 3 4 5% 55%	3516
November	1st to 10th	Day	1 8% 3 8% 4 4 4 3 5% 5% 55%	1853
	11th to 20th	Day	10% 4 7% 5% 3 3 2 5% 7% 53%	1890
	21st to end	Day	8% 5% 12% 6% 3 3 2 4 6% 52%	1724
December	1st to 10th	Day	4 3 11% 9% 6% 4 2 3 6% 53%	2700
	11th to 20th	Day	6% 5% 13% 4 3 3 3 4 7% 52%	3106
	21st to end	Day	9% 5% 15% 8% 6% 5% 4 6% 8% 36%	4092
January	1st to 10th	Night	4 5% 20% 11% 6% 4 3 5% 5% 37%	8201
	11th to 20th	Night	2 5% 15% 10% 7% 8% 2 4 4 43%	7968
	21st to end	Night	2 5% 15% 9% 6% 6% 3 4 5% 44%	8370
February	1st to 10th	Night	6% 6% 15% 9% 7% 5% 3 5% 7% 38%	2730
	11th to 20th	Night	5% 5% 16% 10% 6% 5% 4 5% 6% 38%	2532
	21st to end	Night	5% 5% 16% 8% 7% 4 3 4 5% 42%	2076
March	1st to 10th	Night	4 6% 22% 6% 5% 4 3 4 4 42%	5409
	11th to 20th	Night	5% 6% 15% 7% 4 3 3 4 6% 46%	5110
	21st to end	Night	1 14% 9% 17% 5% 4 4 3 5% 5% 32%	5340
April	1st to 10th	Night	9% 4 11% 6% 5% 4 4 6% 6% 46%	2100
	11th to 20th	Night	1 11% 4 13% 6% 5% 4 3 4 7% 42%	2077
	21st to end	Night	2 13% 5% 9% 3 3 4 3 5% 7% 45%	2100
May	1st to 10th	Night	1 14% 5% 11% 4 4 5% 4 6% 7% 38%	5526
	11th to 20th	Night	2 11% 5% 7% 4 4 5% 4 6% 8% 44%	4701
	21st to end	Night	2 10% 3 7% 4 4 4 3 5% 8% 49%	5181
June	1st to 10th	Night	3 4 1 4 3 4 5% 4 7% 8% 55%	1680
	11th to 20th	Night	3 4 1 3 3 3 3 4 5% 7% 63%	1680
	21st to end	Night	2 5% 2 4 3 4 4 3 7% 9% 59%	1680
July	1st to 10th	Night	2 3 1 4 3 4 4 3 7% 8% 59%	4740
	11th to 20th	Night	1 2 1 3 3 4 5% 6% 9% 10% 56%	4740
	21st to end	Night	2 3 1 5% 4 6% 7% 6% 9% 11% 45%	5527
August	1st to 10th	Night	3 4 2 4 3 4 5% 5% 7% 10% 54%	5273
	11th to 20th	Night	2 3 1 4 4 4 5% 5% 9% 11% 52%	5721
	21st to end	Night	3 5% 2 7% 6% 6% 8% 6% 9% 11% 38%	6465
September	1st to 10th	Night	3 4 2 5% 4 4 4 4 7% 7% 57%	2100
	11th to 20th	Night	4 5% 1 4 4 4 4 3 6% 7% 58%	2100
	21st to end	Night	4 6% 2 6% 4 3 4 3 5% 7% 57%	2340
October	1st to 10th	Night	1 4 1 3 3 3 3 2 4 5% 71%	4040
	11th to 20th	Night	1 5% 2 7% 4 4 4 4 5% 7% 58%	3934
	21st to end	Night	2 6% 3 7% 3 3 3 2 4 7% 61%	4252
November	1st to 10th	Night	5% 4 8% 4 3 3 3 4 6% 60%	2665
	11th to 20th	Night	5% 4 10% 5% 4 3 3 4 7% 54%	2730
	21st to end	Night	5% 5% 10% 6% 4 3 3 5% 8% 50%	2893
December	1st to 10th	Night	3 3 9% 6% 7% 4 3 3 4 59%	4710
	11th to 20th	Night	4 3 12% 6% 5% 4 4 5% 7% 50%	5321
	21st to end	Night	8% 6% 17% 7% 6% 5% 3 5% 7% 35%	7128

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	42% 6% 10% 24% 12% 6%	4723
	11th to 20th	Day	32% 7% 11% 23% 17% 9%	5077
	21st to end	Day	37% 5% 7% 21% 19% 11%	5844
February	1st to 10th	Day	38% 7% 16% 19% 14% 5%	1890
	11th to 20th	Day	38% 5% 13% 21% 17% 6%	1982
	21st to end	Day	38% 5% 10% 20% 21% 7%	1730
March	1st to 10th	Day	37% 3 6% 19% 24% 11%	4687
	11th to 20th	Day	45% 8% 7% 24% 14% 3	5110
	21st to end	Day	48% 3 12% 24% 11% 1	5865
April	1st to 10th	Day	41% 5% 12% 21% 16% 6%	2520
	11th to 20th	Day	49% 4 10% 18% 16% 4	2494
	21st to end	Day	50% 5% 9% 24% 10% 2	2520
May	1st to 10th	Day	54% 4 6% 20% 14% 2	7417
	11th to 20th	Day	47% 5% 7% 22% 17% 1	8195
	21st to end	Day	43% 4 8% 23% 18% 4	9027
June	1st to 10th	Day	37% 8% 11% 21% 18% 6%	2940
	11th to 20th	Day	35% 6% 7% 17% 24% 11%	2940
	21st to end	Day	35% 7% 7% 19% 22% 10%	2940
July	1st to 10th	Day	37% 3 3 11% 28% 18%	8181
	11th to 20th	Day	43% 4 8% 18% 16% 10%	8175
	21st to end	Day	52% 4 12% 11% 13% 8%	8375
August	1st to 10th	Day	44% 4 10% 15% 17% 11%	5978
	11th to 20th	Day	48% 5% 12% 15% 14% 5%	5628
	21st to end	Day	49% 4 15% 14% 14% 5%	6078
September	1st to 10th	Day	38% 5% 7% 16% 24% 11%	2520
	11th to 20th	Day	38% 4 10% 17% 24% 8%	2520
	21st to end	Day	34% 4 6% 23% 26% 6%	2274
October	1st to 10th	Day	22% 4 4 28% 34% 8%	3370
	11th to 20th	Day	37% 3 8% 28% 19% 5%	3280
	21st to end	Day	31% 3 6% 30% 26% 4	3516
November	1st to 10th	Day	25% 5% 13% 22% 30% 6%	1853
	11th to 20th	Day	24% 5% 15% 28% 20% 8%	1890
	21st to end	Day	30% 5% 11% 26% 17% 10%	1724
December	1st to 10th	Day	27% 5% 10% 34% 18% 7%	2700
	11th to 20th	Day	25% 7% 16% 30% 20% 2	3104
	21st to end	Day	36% 6% 12% 17% 23% 6%	4092
January	1st to 10th	Night	40% 4 10% 26% 14% 6%	8202
	11th to 20th	Night	33% 7% 11% 24% 17% 9%	7968
	21st to end	Night	29% 7% 10% 19% 22% 13%	8370
February	1st to 10th	Night	31% 8% 16% 22% 18% 5%	2730
	11th to 20th	Night	31% 6% 15% 24% 19% 4	2533
	21st to end	Night	30% 5% 14% 21% 21% 9%	2076
March	1st to 10th	Night	35% 5% 8% 17% 25% 10%	5409
	11th to 20th	Night	32% 7% 9% 22% 26% 4	5110
	21st to end	Night	41% 5% 18% 26% 10% 1	5340
April	1st to 10th	Night	29% 6% 15% 26% 20% 5%	2100
	11th to 20th	Night	34% 6% 13% 26% 17% 3	2077
	21st to end	Night	33% 6% 14% 29% 16% 1	2100
May	1st to 10th	Night	40% 4 10% 29% 15% 2	5524
	11th to 20th	Night	36% 6% 13% 29% 16%	4702
	21st to end	Night	32% 3 13% 30% 20% 2	5182
June	1st to 10th	Night	22% 7% 18% 31% 17% 6%	1680
	11th to 20th	Night	19% 6% 12% 23% 29% 11%	1680
	21st to end	Night	21% 6% 11% 23% 26% 13%	1680
July	1st to 10th	Night	25% 3 6% 16% 35% 15%	4700
	11th to 20th	Night	23% 3 16% 32% 21% 5%	4692
	21st to end	Night	33% 7% 23% 18% 11% 7%	5405
August	1st to 10th	Night	29% 4 17% 24% 18% 8%	4168
	11th to 20th	Night	29% 8% 26% 18% 13% 5%	4504
	21st to end	Night	37% 6% 23% 15% 16% 2	5069
September	1st to 10th	Night	26% 6% 11% 25% 25% 8%	2100
	11th to 20th	Night	24% 6% 13% 25% 23% 9%	2100
	21st to end	Night	26% 6% 8% 30% 24% 6%	2340
October	1st to 10th	Night	15% 4 7% 33% 34% 8%	4040
	11th to 20th	Night	25% 3 10% 39% 19% 5%	3934
	21st to end	Night	22% 3 8% 31% 30% 6%	4252
November	1st to 10th	Night	19% 5% 14% 26% 28% 7%	2665
	11th to 20th	Night	22% 5% 14% 30% 22% 7%	2730
	21st to end	Night	27% 6% 12% 28% 20% 7%	2893
December	1st to 10th	Night	20% 5% 12% 34% 22% 6%	4710
	11th to 20th	Night	24% 6% 13% 30% 24% 3	5322
	21st to end	Night	40% 5% 10% 18% 20% 6%	7128

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	25% 25% 25% 19% 5% 2	330
	11th to 20th	Day	23% 30% 30% 12% 4 1	330
	21st to end	Day	20% 31% 31% 14% 3 1	363
February	1st to 10th	Day	32% 33% 24% 9% 2 1	330
	11th to 20th	Day	34% 31% 25% 8% 2	330
	21st to end	Day	34% 33% 23% 10% 1	273
March	1st to 10th	Day	25% 26% 28% 18% 2	365
	11th to 20th	Day	25% 26% 30% 15% 3 1	540
	21st to end	Day	20% 39% 30% 10% 2	594
April	1st to 10th	Day	24% 34% 29% 10% 3 1	540
	11th to 20th	Day	30% 34% 26% 8% 2 1	532
	21st to end	Day	21% 35% 33% 8% 3 1	540
May	1st to 10th	Day	19% 31% 30% 15% 4 1	611
	11th to 20th	Day	20% 18% 32% 22% 7% 1	775
	21st to end	Day	17% 20% 29% 22% 11% 2	844
June	1st to 10th	Day	12% 16% 29% 25% 15% 2	780
	11th to 20th	Day	16% 18% 31% 23% 10% 2	780
	21st to end	Day	11% 18% 31% 24% 15% 2	780
July	1st to 10th	Day	11% 9% 27% 30% 19% 3	771
	11th to 20th	Day	8% 11% 25% 32% 19% 5%	768
	21st to end	Day	12% 9% 27% 29% 18% 5%	713
August	1st to 10th	Day	16% 14% 32% 24% 11% 2	567
	11th to 20th	Day	12% 13% 30% 26% 15% 4	557
	21st to end	Day	16% 12% 32% 26% 12% 3	627
September	1st to 10th	Day	15% 15% 31% 23% 12% 4	570
	11th to 20th	Day	16% 15% 37% 22% 9% 1	570
	21st to end	Day	14% 20% 27% 20% 14% 5%	376
October	1st to 10th	Day	13% 21% 27% 20% 15% 4	360
	11th to 20th	Day	22% 29% 23% 16% 7% 3	339
	21st to end	Day	24% 28% 24% 18% 5% 1	363
November	1st to 10th	Day	25% 29% 25% 13% 8%	330
	11th to 20th	Day	22% 28% 28% 16% 5% 1	330
	21st to end	Day	18% 26% 38% 17% 2	330
December	1st to 10th	Day	28% 26% 26% 15% 5% 1	330
	11th to 20th	Day	25% 29% 30% 12% 3 1	330
	21st to end	Day	27% 30% 28% 11% 4 1	363
January	1st to 10th	Night	17% 23% 29% 23% 8% 1	1050
	11th to 20th	Night	18% 22% 33% 20% 6% 1	950
	21st to end	Night	10% 21% 43% 20% 6%	924
February	1st to 10th	Night	13% 25% 42% 15% 5%	840
	11th to 20th	Night	14% 25% 38% 19% 3	824
	21st to end	Night	12% 27% 40% 19% 2	692
March	1st to 10th	Night	10% 22% 40% 24% 5%	840
	11th to 20th	Night	10% 19% 36% 29% 6% 1	840
	21st to end	Night	8% 21% 45% 21% 4	809
April	1st to 10th	Night	11% 22% 42% 23% 2	630
	11th to 20th	Night	10% 23% 38% 24% 5%	623
	21st to end	Night	11% 17% 38% 27% 7% 1	630
May	1st to 10th	Night	11% 12% 40% 30% 8%	630
	11th to 20th	Night	11% 9% 30% 38% 11%	621
	21st to end	Night	10% 11% 29% 35% 13% 1	683
June	1st to 10th	Night	6% 8% 26% 41% 18% 1	630
	11th to 20th	Night	5% 11% 31% 42% 10% 1	630
	21st to end	Night	5% 4 25% 45% 20% 1	630
July	1st to 10th	Night	7% 2 15% 43% 30% 2	615
	11th to 20th	Night	3 1 12% 48% 33% 3	612
	21st to end	Night	6% 2 13% 39% 37% 3	690
August	1st to 10th	Night	8% 2 16% 43% 28% 2	627
	11th to 20th	Night	6% 2 15% 49% 25% 2	624
	21st to end	Night	6% 2 15% 47% 27% 3	693
September	1st to 10th	Night	4 3 19% 47% 24% 3	630
	11th to 20th	Night	6% 5% 23% 46% 19% 2	630
	21st to end	Night	6% 6% 29% 38% 18% 3	677
October	1st to 10th	Night	6% 11% 33% 34% 14% 2	840
	11th to 20th	Night	10% 20% 31% 28% 11% 1	812
	21st to end	Night	10% 16% 37% 28% 8% 2	880
November	1st to 10th	Night	8% 22% 38% 24% 7% 1	1025
	11th to 20th	Night	13% 22% 38% 21% 4 1	1050
	21st to end	Night	10% 19% 40% 27% 5%	1050
December	1st to 10th	Night	12% 25% 38% 21% 4	1050
	11th to 20th	Night	15% 24% 36% 19% 5%	1050
	21st to end	Night	16% 23% 36% 19% 5% 1	1155

Page generated at 2026-10-11 03:06:30. Version ac07

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