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 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	4 9% 5% 12% 6% 5% 5% 4 5% 6% 40%	101331
	Night	1 6% 4 11% 6% 5% 5% 4 6% 7% 46%	97897
Transparency	Day	39% 6% 10% 20% 18% 7%	101079
	Night	28% 7% 15% 25% 19% 6%	97739
Seeing	Day	17% 22% 29% 20% 10% 2	15547
	Night	9% 16% 32% 30% 12% 1	25569

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	5% 4 16% 13% 11% 4 2 4 6% 36%	2538
	11th to 20th	Day	8% 5% 19% 10% 10% 6% 2 3 4 31%	2709
	21st to end	Day	7% 7% 16% 7% 5% 4 3 4 5% 42%	3146
February	1st to 10th	Day	8% 7% 17% 11% 5% 5% 3 5% 6% 32%	1710
	11th to 20th	Day	5% 7% 19% 9% 7% 3 3 3 5% 40%	1780
	21st to end	Day	6% 5% 21% 8% 7% 4 2 5% 5% 37%	1570
March	1st to 10th	Day	7% 7% 22% 7% 4 3 2 3 4 40%	3187
	11th to 20th	Day	1 9% 8% 16% 5% 5% 4 3 5% 6% 39%	3490
	21st to end	Day	1 14% 11% 20% 7% 4 4 3 4 4 28%	4000
April	1st to 10th	Day	2 12% 6% 13% 6% 5% 5% 3 5% 5% 38%	2280
	11th to 20th	Day	2 20% 8% 14% 6% 4 3 2 4 5% 31%	2251
	21st to end	Day	2 21% 7% 13% 6% 4 4 4 4 5% 30%	2280
May	1st to 10th	Day	3 18% 12% 16% 6% 4 4 4 5% 5% 23%	4001
	11th to 20th	Day	4 15% 4 9% 7% 6% 5% 5% 6% 7% 34%	4388
	21st to end	Day	4 10% 3 8% 6% 5% 6% 5% 6% 8% 40%	4825
June	1st to 10th	Day	6% 8% 3 6% 4 5% 6% 5% 7% 9% 43%	2660
	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	5% 11% 3 6% 4 5% 3 3 5% 6% 49%	1900
	11th to 20th	Day	4 10% 2 6% 4 3 3 3 4 6% 56%	1900
	21st to end	Day	3 11% 4 9% 4 3 3 2 4 5% 51%	2071
November	1st to 10th	Day	1 8% 3 8% 4 4 3 3 5% 5% 56%	1682
	11th to 20th	Day	11% 4 8% 5% 3 3 2 5% 7% 51%	1710
	21st to end	Day	7% 4 11% 6% 3 3 3 5% 6% 52%	1560
December	1st to 10th	Day	6% 5% 17% 11% 5% 4 3 4 7% 38%	1520
	11th to 20th	Day	8% 4 13% 6% 5% 5% 3 5% 9% 41%	1926
	21st to end	Day	6% 5% 15% 10% 7% 5% 4 6% 7% 35%	2794
January	1st to 10th	Night	3 4 16% 13% 8% 5% 4 5% 5% 37%	4417
	11th to 20th	Night	4 6% 19% 12% 5% 8% 2 4 4 35%	4288
	21st to end	Night	5% 7% 17% 10% 6% 5% 4 4 5% 38%	4521
February	1st to 10th	Night	5% 6% 16% 10% 7% 4 3 5% 7% 36%	2470
	11th to 20th	Night	5% 5% 15% 10% 6% 5% 4 5% 6% 40%	2286
	21st to end	Night	4 5% 17% 9% 7% 5% 3 4 6% 39%	1884
March	1st to 10th	Night	4 6% 20% 6% 5% 4 3 5% 5% 43%	3677
	11th to 20th	Night	1 6% 7% 13% 6% 4 3 3 5% 7% 46%	3490
	21st to end	Night	11% 8% 16% 6% 5% 4 4 5% 6% 34%	3647
April	1st to 10th	Night	9% 4 11% 6% 5% 4 4 6% 6% 46%	1900
	11th to 20th	Night	1 12% 5% 13% 6% 5% 4 3 4 7% 41%	1877
	21st to end	Night	2 14% 5% 10% 3 3 4 3 5% 7% 43%	1900
May	1st to 10th	Night	2 12% 5% 14% 4 4 5% 3 6% 7% 38%	2965
	11th to 20th	Night	2 9% 2 8% 6% 5% 6% 5% 8% 9% 39%	2517
	21st to end	Night	2 10% 3 6% 4 4 4 3 5% 8% 50%	2762
June	1st to 10th	Night	3 4 1 5% 3 4 5% 4 7% 8% 55%	1520
	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	3 7% 2 5% 4 4 4 3 5% 6% 57%	2280
	11th to 20th	Night	1 6% 2 6% 3 2 3 3 4 5% 64%	2280
	21st to end	Night	3 8% 3 8% 4 4 3 2 4 7% 54%	2508
November	1st to 10th	Night	5% 4 7% 4 3 3 3 4 7% 60%	2431
	11th to 20th	Night	6% 5% 10% 5% 4 3 3 4 7% 54%	2470
	21st to end	Night	5% 5% 10% 6% 4 3 3 5% 8% 50%	2617
December	1st to 10th	Night	4 5% 12% 8% 5% 5% 4 4 6% 47%	2660
	11th to 20th	Night	6% 4 11% 8% 6% 5% 5% 6% 8% 42%	3271
	21st to end	Night	5% 4 14% 8% 7% 5% 3 5% 8% 40%	4873

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	33% 10% 15% 20% 17% 5%	2539
	11th to 20th	Day	40% 10% 17% 21% 10% 3	2709
	21st to end	Day	37% 7% 13% 22% 14% 6%	3146
February	1st to 10th	Day	40% 8% 17% 18% 13% 5%	1710
	11th to 20th	Day	35% 5% 14% 21% 18% 7%	1789
	21st to end	Day	39% 5% 11% 21% 18% 6%	1570
March	1st to 10th	Day	39% 5% 8% 23% 20% 6%	3187
	11th to 20th	Day	42% 10% 10% 26% 10% 3	3490
	21st to end	Day	48% 5% 13% 23% 11% 2	4000
April	1st to 10th	Day	40% 5% 12% 20% 16% 6%	2280
	11th to 20th	Day	50% 4 11% 17% 14% 3	2254
	21st to end	Day	49% 5% 10% 24% 11% 1	2280
May	1st to 10th	Day	50% 8% 8% 18% 14% 2	4001
	11th to 20th	Day	41% 9% 12% 22% 15% 1	4392
	21st to end	Day	33% 7% 9% 22% 24% 5%	4825
June	1st to 10th	Day	36% 8% 12% 21% 17% 6%	2660
	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	33% 7% 7% 21% 25% 7%	1900
	11th to 20th	Day	27% 4 7% 29% 26% 7%	1900
	21st to end	Day	32% 4 10% 26% 21% 7%	2071
November	1st to 10th	Day	23% 5% 13% 22% 30% 6%	1682
	11th to 20th	Day	24% 6% 16% 28% 20% 7%	1710
	21st to end	Day	29% 6% 12% 26% 17% 11%	1560
December	1st to 10th	Day	34% 8% 16% 24% 14% 4	1520
	11th to 20th	Day	28% 10% 14% 27% 18% 3	1924
	21st to end	Day	35% 7% 14% 17% 20% 8%	2794
January	1st to 10th	Night	31% 7% 16% 25% 15% 5%	4417
	11th to 20th	Night	33% 9% 17% 25% 11% 5%	4288
	21st to end	Night	28% 9% 17% 25% 15% 6%	4521
February	1st to 10th	Night	32% 8% 18% 21% 16% 4	2470
	11th to 20th	Night	29% 6% 17% 24% 20% 5%	2287
	21st to end	Night	31% 6% 15% 22% 19% 8%	1884
March	1st to 10th	Night	30% 5% 11% 24% 22% 8%	3677
	11th to 20th	Night	30% 11% 12% 29% 14% 4	3490
	21st to end	Night	32% 7% 22% 26% 12% 1	3647
April	1st to 10th	Night	28% 7% 16% 24% 20% 5%	1900
	11th to 20th	Night	35% 7% 14% 26% 16% 3	1877
	21st to end	Night	34% 6% 15% 29% 15% 1	1900
May	1st to 10th	Night	32% 8% 12% 28% 17% 3	2965
	11th to 20th	Night	33% 11% 16% 25% 15%	2518
	21st to end	Night	24% 6% 14% 29% 23% 3	2762
June	1st to 10th	Night	22% 8% 19% 29% 16% 6%	1520
	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	22% 6% 12% 27% 24% 9%	2280
	11th to 20th	Night	17% 5% 11% 33% 26% 8%	2280
	21st to end	Night	25% 5% 13% 28% 22% 6%	2508
November	1st to 10th	Night	18% 6% 15% 26% 28% 7%	2431
	11th to 20th	Night	22% 5% 15% 30% 21% 7%	2470
	21st to end	Night	26% 6% 11% 28% 20% 8%	2617
December	1st to 10th	Night	23% 9% 21% 24% 17% 6%	2660
	11th to 20th	Night	26% 10% 15% 23% 22% 4	3272
	21st to end	Night	32% 8% 13% 19% 19% 9%	4873

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	21% 24% 24% 22% 6% 2	270
	11th to 20th	Day	21% 30% 30% 14% 4 1	270
	21st to end	Day	13% 34% 33% 16% 4 1	297
February	1st to 10th	Day	25% 37% 25% 10% 1 1	270
	11th to 20th	Day	29% 32% 27% 10% 2	270
	21st to end	Day	31% 35% 23% 10% 1	225
March	1st to 10th	Day	25% 26% 28% 18% 3	301
	11th to 20th	Day	19% 27% 33% 17% 3 1	460
	21st to end	Day	18% 39% 30% 11% 2	506
April	1st to 10th	Day	22% 36% 27% 10% 3 1	460
	11th to 20th	Day	28% 35% 25% 9% 2 1	452
	21st to end	Day	20% 34% 33% 9% 3 1	460
May	1st to 10th	Day	19% 30% 31% 15% 5% 1	525
	11th to 20th	Day	18% 17% 32% 23% 8% 1	675
	21st to end	Day	16% 19% 29% 22% 12% 2	734
June	1st to 10th	Day	11% 15% 29% 26% 16% 3	680
	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	25% 27% 25% 18% 5% 1	330
November	1st to 10th	Day	23% 30% 25% 14% 8%	273
	11th to 20th	Day	21% 28% 27% 17% 5% 1	270
	21st to end	Day	13% 26% 40% 19% 2	270
December	1st to 10th	Day	21% 29% 28% 15% 5% 1	270
	11th to 20th	Day	19% 32% 32% 13% 4 1	270
	21st to end	Day	22% 34% 27% 13% 4 1	297
January	1st to 10th	Night	15% 23% 29% 24% 8% 1	950
	11th to 20th	Night	17% 22% 33% 21% 6% 1	860
	21st to end	Night	9% 21% 42% 21% 6%	836
February	1st to 10th	Night	11% 25% 43% 15% 5%	760
	11th to 20th	Night	11% 26% 38% 21% 3	744
	21st to end	Night	10% 28% 41% 19% 2	628
March	1st to 10th	Night	9% 23% 39% 25% 5%	760
	11th to 20th	Night	6% 19% 37% 31% 6% 1	760
	21st to end	Night	7% 22% 46% 21% 4	732
April	1st to 10th	Night	11% 22% 41% 24% 2	570
	11th to 20th	Night	10% 23% 37% 24% 6% 1	563
	21st to end	Night	11% 18% 37% 27% 7% 1	570
May	1st to 10th	Night	10% 11% 40% 30% 8% 1	570
	11th to 20th	Night	10% 9% 30% 39% 12%	561
	21st to end	Night	10% 11% 29% 35% 14% 1	617
June	1st to 10th	Night	5% 7% 25% 42% 19% 1	570
	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% 21% 39% 25% 8% 1	935
	11th to 20th	Night	13% 23% 37% 22% 5% 1	950
	21st to end	Night	9% 19% 38% 29% 6%	950
December	1st to 10th	Night	10% 26% 39% 21% 4	950
	11th to 20th	Night	12% 25% 37% 20% 5%	950
	21st to end	Night	14% 24% 36% 20% 5% 1	1045

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