Red Lodge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Red Lodge clear sky chart from 2005-11-06 to 2025-04-11.

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 6% 2 6% 5% 5% 5% 5% 7% 9% 46%	118469
	Night	4 6% 2 6% 4 4 5% 4 6% 8% 51%	118743
Transparency	Day	30% 11% 16% 23% 16% 4	118210
	Night	27% 10% 17% 26% 16% 4	118592
Seeing	Day	9% 17% 39% 25% 9% 1	16384
	Night	7% 11% 44% 30% 9% 1	26048

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 6% 4 10% 6% 7% 6% 5% 9% 10% 37%	3638
	11th to 20th	Day	1 3 2 9% 10% 8% 8% 6% 8% 10% 37%	3796
	21st to end	Day	1 3 2 6% 4 4 5% 4 6% 9% 56%	4510
February	1st to 10th	Day	2 9% 3 9% 7% 6% 7% 6% 8% 9% 35%	1800
	11th to 20th	Day	1 7% 4 10% 7% 7% 7% 5% 6% 9% 37%	1755
	21st to end	Day	1 7% 3 10% 7% 5% 6% 4 7% 10% 40%	1498
March	1st to 10th	Day	2 7% 4 7% 4 5% 5% 4 6% 8% 48%	4926
	11th to 20th	Day	2 9% 3 9% 5% 5% 5% 5% 7% 10% 41%	5000
	21st to end	Day	4 13% 4 11% 7% 6% 7% 5% 8% 9% 25%	5486
April	1st to 10th	Day	6% 12% 3 8% 5% 5% 5% 4 6% 8% 37%	2385
	11th to 20th	Day	7% 12% 4 10% 6% 5% 5% 5% 7% 8% 32%	2325
	21st to end	Day	11% 13% 3 8% 5% 4 5% 4 6% 8% 32%	2470
May	1st to 10th	Day	13% 16% 4 9% 5% 5% 5% 5% 7% 6% 26%	4205
	11th to 20th	Day	8% 7% 2 6% 4 4 6% 5% 9% 10% 40%	4388
	21st to end	Day	13% 9% 3 7% 5% 5% 6% 5% 7% 9% 31%	4825
June	1st to 10th	Day	10% 6% 2 5% 6% 5% 5% 4 8% 8% 41%	2660
	11th to 20th	Day	7% 5% 2 5% 6% 5% 6% 6% 8% 8% 42%	2830
	21st to end	Day	3 2 1 4 4 4 5% 4 7% 9% 57%	2850
July	1st to 10th	Day	3 2 1 3 4 4 5% 5% 7% 9% 56%	4740
	11th to 20th	Day	2 1 1 3 4 4 6% 5% 8% 9% 58%	4471
	21st to end	Day	2 2 1 3 3 5% 6% 6% 7% 9% 56%	4653
August	1st to 10th	Day	6% 5% 2 6% 5% 6% 6% 5% 7% 8% 44%	4092
	11th to 20th	Day	3 2 1 3 4 5% 6% 6% 8% 9% 52%	4028
	21st to end	Day	4 2 1 3 3 4 5% 4 6% 7% 61%	4402
September	1st to 10th	Day	6% 4 1 4 3 3 4 3 6% 6% 61%	2280
	11th to 20th	Day	7% 6% 2 4 4 4 4 4 5% 8% 53%	2190
	21st to end	Day	7% 5% 2 4 3 3 4 4 5% 6% 58%	2055
October	1st to 10th	Day	7% 5% 1 4 3 3 2 2 4 5% 64%	3170
	11th to 20th	Day	5% 5% 2 5% 3 2 2 3 3 6% 63%	3150
	21st to end	Day	3 8% 2 6% 4 3 4 3 6% 9% 51%	3438
November	1st to 10th	Day	3 8% 2 8% 5% 4 4 4 5% 8% 49%	1603
	11th to 20th	Day	3 6% 3 5% 4 3 5% 4 7% 9% 50%	1600
	21st to end	Day	2 7% 2 7% 4 4 4 5% 7% 7% 49%	1600
December	1st to 10th	Day	4 3 6% 3 4 5% 4 5% 8% 56%	2620
	11th to 20th	Day	1 3 2 5% 5% 5% 5% 5% 9% 12% 48%	3026
	21st to end	Day	3 6% 3 8% 6% 6% 6% 5% 6% 8% 44%	4004
January	1st to 10th	Night	1 6% 3 9% 5% 5% 5% 5% 7% 9% 45%	6327
	11th to 20th	Night	4 2 7% 6% 8% 9% 6% 9% 8% 42%	6229
	21st to end	Night	1 4 2 5% 4 4 6% 5% 7% 8% 54%	6468
February	1st to 10th	Night	1 7% 3 10% 8% 6% 6% 5% 7% 9% 39%	2600
	11th to 20th	Night	1 7% 4 9% 6% 5% 5% 6% 7% 9% 41%	2532
	21st to end	Night	1 5% 4 9% 6% 5% 4 4 7% 7% 48%	2131
March	1st to 10th	Night	2 7% 3 6% 4 4 5% 4 5% 7% 52%	4952
	11th to 20th	Night	2 8% 2 6% 3 3 4 4 7% 11% 49%	5000
	21st to end	Night	4 8% 4 9% 6% 7% 6% 5% 7% 10% 35%	5489
April	1st to 10th	Night	6% 10% 3 5% 5% 4 4 4 6% 10% 43%	2015
	11th to 20th	Night	6% 10% 4 9% 5% 5% 5% 5% 7% 8% 36%	1805
	21st to end	Night	8% 13% 4 7% 3 4 4 3 6% 7% 42%	1710
May	1st to 10th	Night	13% 13% 2 6% 4 4 4 4 6% 7% 37%	2764
	11th to 20th	Night	8% 6% 2 4 4 4 4 4 7% 9% 49%	2517
	21st to end	Night	13% 8% 3 5% 5% 4 4 5% 6% 8% 40%	2762
June	1st to 10th	Night	10% 6% 1 4 4 4 5% 6% 7% 11% 43%	1520
	11th to 20th	Night	8% 4 2 5% 5% 5% 4 4 6% 10% 49%	1344
	21st to end	Night	4 3 1 3 2 2 3 4 5% 9% 63%	1330
July	1st to 10th	Night	4 2 1 3 3 3 3 4 7% 8% 63%	2220
	11th to 20th	Night	2 2 1 2 2 3 4 5% 7% 8% 64%	2494
	21st to end	Night	2 2 1 3 2 3 4 3 7% 10% 63%	2908
August	1st to 10th	Night	6% 4 1 4 3 5% 5% 5% 7% 8% 53%	2847
	11th to 20th	Night	3 2 1 4 4 4 5% 5% 7% 9% 56%	2811
	21st to end	Night	6% 3 1 3 2 2 3 3 4 6% 67%	3265
September	1st to 10th	Night	5% 4 2 3 2 3 3 2 4 6% 65%	1900
	11th to 20th	Night	8% 4 2 4 3 3 3 3 4 7% 59%	1985
	21st to end	Night	8% 4 1 3 3 3 3 3 5% 7% 59%	2123
October	1st to 10th	Night	6% 5% 2 3 2 2 2 2 4 7% 65%	3800
	11th to 20th	Night	5% 7% 2 6% 3 2 2 2 3 7% 60%	3778
	21st to end	Night	4 6% 2 6% 4 4 4 4 6% 6% 56%	4120
November	1st to 10th	Night	4 7% 2 6% 4 4 4 3 6% 9% 51%	2672
	11th to 20th	Night	3 7% 2 6% 5% 4 4 3 7% 9% 51%	2800
	21st to end	Night	2 7% 2 6% 5% 5% 4 4 6% 9% 50%	2800
December	1st to 10th	Night	1 3 2 5% 4 4 4 4 6% 8% 59%	4570
	11th to 20th	Night	2 4 2 5% 3 4 5% 6% 8% 10% 51%	5181
	21st to end	Night	1 6% 3 7% 5% 4 5% 4 8% 10% 47%	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	35% 13% 18% 27% 7%	3639
	11th to 20th	Day	31% 14% 22% 17% 13% 2	3796
	21st to end	Day	20% 11% 21% 28% 19% 1	4510
February	1st to 10th	Day	41% 15% 18% 17% 8% 1	1800
	11th to 20th	Day	39% 15% 17% 19% 9% 2	1764
	21st to end	Day	37% 11% 17% 18% 13% 3	1498
March	1st to 10th	Day	29% 10% 16% 27% 15% 4	4926
	11th to 20th	Day	31% 13% 19% 27% 9% 1	5000
	21st to end	Day	44% 19% 17% 16% 3	5486
April	1st to 10th	Day	42% 11% 17% 20% 9% 1	2385
	11th to 20th	Day	45% 11% 20% 19% 5%	2328
	21st to end	Day	46% 12% 17% 19% 6%	2470
May	1st to 10th	Day	51% 10% 15% 17% 6% 1	4205
	11th to 20th	Day	30% 13% 19% 26% 11% 1	4392
	21st to end	Day	41% 12% 17% 23% 6%	4825
June	1st to 10th	Day	37% 13% 20% 21% 9% 1	2660
	11th to 20th	Day	34% 14% 16% 19% 15% 3	2830
	21st to end	Day	21% 9% 17% 25% 20% 7%	2850
July	1st to 10th	Day	19% 9% 12% 28% 27% 5%	4666
	11th to 20th	Day	17% 8% 10% 19% 31% 15%	4394
	21st to end	Day	18% 8% 12% 19% 28% 15%	4506
August	1st to 10th	Day	31% 12% 14% 17% 19% 8%	4078
	11th to 20th	Day	21% 9% 14% 25% 25% 5%	4067
	21st to end	Day	20% 7% 11% 24% 30% 7%	4401
September	1st to 10th	Day	23% 6% 12% 18% 31% 9%	2280
	11th to 20th	Day	28% 7% 15% 22% 23% 5%	2190
	21st to end	Day	26% 8% 14% 26% 20% 5%	2055
October	1st to 10th	Day	24% 5% 11% 17% 31% 12%	3170
	11th to 20th	Day	23% 6% 15% 29% 23% 4	3150
	21st to end	Day	27% 8% 19% 32% 13% 2	3438
November	1st to 10th	Day	33% 13% 15% 22% 14% 3	1603
	11th to 20th	Day	27% 12% 22% 24% 13% 3	1600
	21st to end	Day	32% 10% 21% 23% 14% 1	1600
December	1st to 10th	Day	24% 11% 21% 24% 15% 4	2620
	11th to 20th	Day	22% 15% 31% 25% 7% 1	3024
	21st to end	Day	33% 11% 12% 23% 16% 5%	4004
January	1st to 10th	Night	31% 12% 18% 29% 10% 1	6327
	11th to 20th	Night	28% 13% 22% 24% 10% 2	6229
	21st to end	Night	23% 11% 20% 28% 15% 4	6468
February	1st to 10th	Night	38% 12% 19% 21% 9% 1	2600
	11th to 20th	Night	36% 15% 18% 19% 11% 1	2533
	21st to end	Night	34% 9% 17% 22% 16% 2	2131
March	1st to 10th	Night	28% 7% 16% 24% 20% 5%	4952
	11th to 20th	Night	25% 11% 20% 30% 13% 1	5000
	21st to end	Night	34% 18% 21% 19% 7% 1	5489
April	1st to 10th	Night	37% 10% 19% 21% 11% 2	2015
	11th to 20th	Night	43% 10% 18% 23% 7%	1805
	21st to end	Night	39% 12% 17% 23% 9%	1710
May	1st to 10th	Night	45% 9% 14% 19% 11% 2	2764
	11th to 20th	Night	29% 11% 17% 34% 7% 3	2518
	21st to end	Night	37% 13% 18% 27% 5%	2762
June	1st to 10th	Night	32% 13% 21% 23% 9% 2	1520
	11th to 20th	Night	30% 13% 17% 22% 14% 4	1344
	21st to end	Night	17% 9% 18% 31% 19% 6%	1330
July	1st to 10th	Night	16% 7% 13% 33% 27% 3	2185
	11th to 20th	Night	14% 8% 9% 21% 34% 16%	2448
	21st to end	Night	13% 6% 11% 23% 33% 15%	2817
August	1st to 10th	Night	25% 9% 15% 21% 20% 10%	2838
	11th to 20th	Night	20% 8% 12% 28% 22% 10%	2838
	21st to end	Night	18% 5% 8% 22% 34% 12%	3265
September	1st to 10th	Night	22% 6% 8% 22% 30% 12%	1900
	11th to 20th	Night	25% 7% 13% 26% 23% 6%	1985
	21st to end	Night	25% 6% 13% 28% 23% 5%	2123
October	1st to 10th	Night	20% 6% 9% 22% 30% 13%	3800
	11th to 20th	Night	26% 6% 15% 27% 20% 6%	3778
	21st to end	Night	26% 8% 11% 33% 15% 7%	4120
November	1st to 10th	Night	30% 11% 17% 25% 14% 3	2672
	11th to 20th	Night	28% 10% 21% 26% 12% 2	2800
	21st to end	Night	28% 11% 20% 25% 14% 2	2800
December	1st to 10th	Night	21% 10% 19% 30% 16% 3	4570
	11th to 20th	Night	23% 12% 23% 32% 9% 1	5182
	21st to end	Night	28% 10% 14% 28% 14% 5%	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	6% 22% 43% 26% 4	300
	11th to 20th	Day	5% 29% 44% 16% 6% 1	300
	21st to end	Day	6% 15% 58% 16% 4 1	330
February	1st to 10th	Day	7% 33% 48% 10% 2	300
	11th to 20th	Day	2 34% 44% 16% 3 1	300
	21st to end	Day	4 29% 43% 21% 2	249
March	1st to 10th	Day	7% 23% 50% 16% 3 1	485
	11th to 20th	Day	4 23% 47% 21% 4	500
	21st to end	Day	12% 23% 40% 20% 3 1	550
April	1st to 10th	Day	14% 26% 44% 14% 2	500
	11th to 20th	Day	13% 27% 43% 15% 1	453
	21st to end	Day	22% 17% 33% 20% 7% 1	460
May	1st to 10th	Day	16% 17% 31% 26% 9% 1	519
	11th to 20th	Day	16% 11% 32% 26% 13% 2	675
	21st to end	Day	18% 13% 26% 27% 13% 3	734
June	1st to 10th	Day	10% 11% 34% 29% 13% 3	680
	11th to 20th	Day	10% 19% 39% 23% 8% 1	680
	21st to end	Day	5% 9% 36% 34% 14% 1	680
July	1st to 10th	Day	4 7% 35% 36% 17% 2	671
	11th to 20th	Day	3 7% 35% 41% 14%	668
	21st to end	Day	3 4 32% 40% 19% 2	652
August	1st to 10th	Day	6% 8% 37% 35% 12% 2	487
	11th to 20th	Day	5% 8% 32% 38% 15% 2	477
	21st to end	Day	4 14% 36% 32% 11% 4	539
September	1st to 10th	Day	7% 10% 36% 34% 12% 1	490
	11th to 20th	Day	11% 12% 37% 27% 11% 2	490
	21st to end	Day	10% 15% 38% 28% 7% 2	455
October	1st to 10th	Day	10% 13% 35% 30% 11% 2	300
	11th to 20th	Day	7% 23% 40% 20% 9% 1	300
	21st to end	Day	7% 27% 43% 18% 5%	330
November	1st to 10th	Day	5% 25% 48% 16% 6%	300
	11th to 20th	Day	7% 31% 44% 15% 3 1	300
	21st to end	Day	7% 26% 47% 18% 2	300
December	1st to 10th	Day	4 30% 46% 18% 3	300
	11th to 20th	Day	5% 31% 49% 15% 1	300
	21st to end	Day	7% 27% 45% 17% 5%	330
January	1st to 10th	Night	3 15% 55% 24% 3	1000
	11th to 20th	Night	4 17% 57% 18% 5%	954
	21st to end	Night	5% 11% 57% 22% 5%	880
February	1st to 10th	Night	4 17% 54% 20% 5%	800
	11th to 20th	Night	4 13% 54% 23% 6% 1	784
	21st to end	Night	3 15% 50% 26% 6%	660
March	1st to 10th	Night	4 13% 51% 25% 7%	800
	11th to 20th	Night	7% 9% 47% 29% 8%	800
	21st to end	Night	8% 13% 44% 28% 7% 1	880
April	1st to 10th	Night	9% 14% 44% 27% 5%	615
	11th to 20th	Night	10% 16% 43% 25% 5%	565
	21st to end	Night	15% 8% 38% 29% 10% 1	570
May	1st to 10th	Night	15% 11% 30% 33% 11% 1	570
	11th to 20th	Night	13% 8% 27% 36% 14% 2	561
	21st to end	Night	16% 8% 28% 35% 13% 1	617
June	1st to 10th	Night	11% 7% 32% 33% 15% 1	570
	11th to 20th	Night	9% 9% 40% 35% 8% 1	394
	21st to end	Night	4 3 27% 49% 16% 1	380
July	1st to 10th	Night	4 1 21% 50% 24% 1	370
	11th to 20th	Night	2 4 30% 53% 12%	521
	21st to end	Night	3 2 28% 47% 19% 2	624
August	1st to 10th	Night	6% 2 25% 48% 18% 1	567
	11th to 20th	Night	4 3 23% 50% 18% 1	564
	21st to end	Night	6% 6% 25% 44% 17% 1	627
September	1st to 10th	Night	7% 5% 29% 42% 16% 2	570
	11th to 20th	Night	9% 4 31% 41% 14% 3	655
	21st to end	Night	10% 7% 34% 33% 15% 2	760
October	1st to 10th	Night	14% 6% 33% 34% 11% 2	760
	11th to 20th	Night	9% 9% 41% 29% 12% 1	760
	21st to end	Night	6% 11% 49% 25% 8% 1	836
November	1st to 10th	Night	7% 11% 55% 22% 5%	934
	11th to 20th	Night	5% 17% 57% 19% 2	1000
	21st to end	Night	5% 13% 55% 24% 3	1000
December	1st to 10th	Night	3 15% 54% 24% 4	1000
	11th to 20th	Night	4 12% 59% 22% 3 1	1000
	21st to end	Night	4 18% 53% 21% 4 1	1100

Page generated at 2025-04-08 07:17:23. Version ac07

Copyright © 2025 Attilla Danko.