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 2024-02-25.

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	5% 6% 2 5% 5% 3 5% 6% 7% 9% 46%	78990
	Night	4 5% 2 5% 5% 3 5% 5% 6% 9% 50%	80370
Transparency	Day	32% 12% 18% 21% 14% 4	78691
	Night	29% 11% 18% 24% 14% 3	80191
Seeing	Day	9% 17% 39% 25% 9% 1	14818
	Night	7% 11% 44% 29% 9% 1	24536

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% 3 7% 6% 5% 6% 6% 9% 10% 44%	2538
	11th to 20th	Day	1 4 2 6% 8% 4 8% 8% 10% 11% 38%	2640
	21st to end	Day	1 4 2 4 5% 3 5% 5% 6% 9% 55%	3146
February	1st to 10th	Day	2 9% 3 8% 8% 4 7% 7% 7% 10% 36%	1710
	11th to 20th	Day	1 7% 4 9% 7% 5% 7% 7% 6% 9% 37%	1665
	21st to end	Day	1 6% 4 9% 8% 4 5% 6% 7% 10% 39%	1379
March	1st to 10th	Day	2 6% 4 7% 6% 4 6% 6% 7% 10% 41%	1966
	11th to 20th	Day	3 7% 4 7% 5% 3 5% 6% 7% 10% 42%	1980
	21st to end	Day	6% 10% 5% 8% 7% 4 6% 6% 7% 9% 31%	2178
April	1st to 10th	Day	6% 11% 4 7% 6% 4 7% 5% 6% 8% 36%	2146
	11th to 20th	Day	8% 11% 4 9% 6% 4 5% 6% 7% 8% 32%	2200
	21st to end	Day	11% 13% 4 7% 5% 3 5% 5% 6% 8% 33%	2340
May	1st to 10th	Day	12% 10% 3 6% 6% 3 6% 6% 7% 7% 33%	2393
	11th to 20th	Day	12% 9% 2 5% 6% 3 6% 7% 8% 9% 32%	2478
	21st to end	Day	18% 8% 3 7% 6% 3 7% 7% 7% 9% 26%	2724
June	1st to 10th	Day	11% 6% 2 5% 6% 3 5% 6% 8% 9% 39%	2520
	11th to 20th	Day	7% 5% 2 5% 6% 4 5% 8% 8% 9% 41%	2681
	21st to end	Day	4 2 1 4 4 3 5% 5% 7% 9% 56%	2700
July	1st to 10th	Day	3 3 1 2 5% 3 6% 7% 8% 10% 53%	2700
	11th to 20th	Day	2 2 1 3 4 3 4 5% 6% 8% 60%	2548
	21st to end	Day	3 2 1 3 3 3 5% 7% 6% 9% 58%	2660
August	1st to 10th	Day	5% 3 2 4 5% 4 5% 6% 7% 8% 50%	2328
	11th to 20th	Day	5% 3 1 3 4 2 5% 7% 7% 8% 56%	2299
	21st to end	Day	4 3 2 4 4 3 5% 5% 6% 8% 55%	2507
September	1st to 10th	Day	6% 4 1 4 3 3 4 3 5% 6% 61%	2160
	11th to 20th	Day	7% 5% 2 3 4 3 4 4 5% 8% 55%	2075
	21st to end	Day	7% 5% 2 4 4 2 4 5% 5% 6% 56%	1947
October	1st to 10th	Day	12% 8% 2 6% 5% 3 4 3 6% 7% 45%	1800
	11th to 20th	Day	6% 6% 2 5% 5% 2 3 5% 4 7% 54%	1800
	21st to end	Day	4 6% 2 5% 5% 3 5% 5% 5% 8% 51%	1980
November	1st to 10th	Day	3 7% 3 7% 5% 3 5% 4 5% 8% 49%	1522
	11th to 20th	Day	3 5% 4 4 4 3 5% 5% 6% 10% 51%	1520
	21st to end	Day	2 7% 3 6% 5% 3 5% 6% 7% 7% 49%	1520
December	1st to 10th	Day	1 4 2 6% 5% 4 6% 7% 6% 11% 47%	1520
	11th to 20th	Day	2 5% 2 4 5% 3 5% 6% 8% 12% 48%	1926
	21st to end	Day	2 6% 3 5% 6% 3 5% 5% 6% 7% 52%	2794
January	1st to 10th	Night	1 4 2 7% 6% 3 5% 6% 6% 9% 50%	4417
	11th to 20th	Night	1 4 2 6% 6% 5% 8% 9% 9% 9% 41%	4361
	21st to end	Night	1 6% 2 5% 5% 3 5% 6% 6% 9% 51%	4521
February	1st to 10th	Night	1 6% 4 9% 8% 4 6% 6% 7% 9% 40%	2470
	11th to 20th	Night	1 6% 4 8% 7% 4 6% 6% 7% 9% 42%	2402
	21st to end	Night	1 5% 4 8% 8% 4 5% 5% 6% 7% 47%	1970
March	1st to 10th	Night	2 6% 3 6% 6% 3 5% 5% 6% 10% 48%	1992
	11th to 20th	Night	3 7% 3 4 4 2 4 6% 6% 10% 50%	1980
	21st to end	Night	6% 8% 3 6% 6% 4 5% 5% 7% 10% 38%	2178
April	1st to 10th	Night	6% 9% 3 5% 5% 3 4 5% 6% 10% 43%	1814
	11th to 20th	Night	7% 10% 4 8% 6% 5% 5% 6% 6% 8% 36%	1705
	21st to end	Night	8% 12% 4 6% 4 3 4 4 5% 7% 42%	1620
May	1st to 10th	Night	10% 8% 3 4 5% 3 4 5% 6% 9% 43%	1566
	11th to 20th	Night	11% 8% 2 4 5% 3 4 5% 7% 10% 40%	1417
	21st to end	Night	15% 7% 3 5% 6% 3 5% 7% 7% 11% 32%	1552
June	1st to 10th	Night	11% 5% 1 4 4 3 5% 7% 6% 11% 42%	1440
	11th to 20th	Night	8% 4 2 4 6% 3 4 5% 5% 10% 48%	1274
	21st to end	Night	4 3 1 2 3 2 3 5% 5% 9% 63%	1260
July	1st to 10th	Night	3 1 1 3 3 3 4 5% 7% 10% 61%	1260
	11th to 20th	Night	2 2 1 2 3 1 3 6% 7% 9% 64%	1408
	21st to end	Night	3 2 1 3 4 2 4 3 6% 8% 65%	1656
August	1st to 10th	Night	5% 3 1 3 4 4 5% 6% 6% 8% 56%	1611
	11th to 20th	Night	4 2 1 2 3 3 4 5% 6% 9% 62%	1602
	21st to end	Night	6% 3 1 3 3 2 4 4 5% 7% 60%	1849
September	1st to 10th	Night	6% 4 2 3 3 3 3 3 5% 6% 64%	1800
	11th to 20th	Night	8% 4 2 3 3 2 3 4 4 7% 59%	1880
	21st to end	Night	9% 4 2 3 4 2 3 4 5% 7% 58%	2011
October	1st to 10th	Night	11% 8% 3 5% 4 2 4 4 5% 8% 47%	2160
	11th to 20th	Night	6% 8% 2 5% 5% 3 3 4 4 7% 54%	2160
	21st to end	Night	4 5% 2 5% 5% 3 4 5% 6% 7% 53%	2376
November	1st to 10th	Night	4 6% 3 6% 5% 2 4 4 6% 9% 50%	2534
	11th to 20th	Night	3 6% 2 5% 5% 3 4 5% 7% 9% 51%	2660
	21st to end	Night	3 6% 2 5% 5% 4 5% 5% 6% 9% 50%	2660
December	1st to 10th	Night	1 4 4 6% 7% 4 6% 6% 7% 9% 47%	2660
	11th to 20th	Night	3 4 2 4 3 2 5% 6% 7% 9% 55%	3271
	21st to end	Night	1 6% 3 5% 5% 3 4 5% 7% 9% 51%	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	31% 13% 18% 30% 8% 1	2539
	11th to 20th	Day	28% 16% 25% 18% 12% 1	2640
	21st to end	Day	23% 12% 26% 28% 11% 1	3146
February	1st to 10th	Day	41% 15% 18% 18% 8% 1	1710
	11th to 20th	Day	39% 15% 17% 19% 9% 1	1674
	21st to end	Day	39% 12% 17% 16% 14% 3	1379
March	1st to 10th	Day	34% 13% 21% 22% 9%	1966
	11th to 20th	Day	34% 14% 20% 20% 9% 2	1980
	21st to end	Day	47% 14% 21% 15% 4	2178
April	1st to 10th	Day	43% 12% 17% 18% 8% 1	2146
	11th to 20th	Day	46% 12% 19% 18% 5%	2203
	21st to end	Day	46% 12% 17% 19% 6%	2340
May	1st to 10th	Day	45% 11% 17% 19% 8% 1	2393
	11th to 20th	Day	42% 15% 18% 20% 5%	2482
	21st to end	Day	49% 15% 17% 14% 4	2724
June	1st to 10th	Day	38% 14% 20% 20% 8% 1	2520
	11th to 20th	Day	35% 14% 16% 18% 15% 3	2681
	21st to end	Day	22% 10% 18% 25% 19% 7%	2700
July	1st to 10th	Day	21% 11% 17% 25% 21% 5%	2626
	11th to 20th	Day	19% 8% 12% 21% 25% 14%	2471
	21st to end	Day	20% 8% 14% 17% 27% 14%	2512
August	1st to 10th	Day	27% 10% 16% 21% 18% 8%	2313
	11th to 20th	Day	22% 8% 15% 25% 22% 8%	2299
	21st to end	Day	25% 7% 14% 21% 22% 10%	2507
September	1st to 10th	Day	24% 6% 12% 18% 30% 9%	2160
	11th to 20th	Day	27% 7% 15% 21% 23% 5%	2075
	21st to end	Day	27% 8% 15% 27% 19% 4	1947
October	1st to 10th	Day	39% 8% 15% 21% 14% 3	1800
	11th to 20th	Day	29% 9% 18% 27% 13% 4	1800
	21st to end	Day	30% 10% 22% 23% 14% 1	1980
November	1st to 10th	Day	33% 14% 16% 21% 14% 3	1522
	11th to 20th	Day	27% 13% 23% 23% 13% 2	1520
	21st to end	Day	32% 10% 21% 23% 14% 1	1520
December	1st to 10th	Day	30% 16% 20% 20% 11% 3	1520
	11th to 20th	Day	24% 17% 29% 22% 7% 1	1924
	21st to end	Day	29% 10% 12% 25% 17% 6%	2794
January	1st to 10th	Night	27% 13% 20% 26% 12% 1	4417
	11th to 20th	Night	29% 14% 26% 20% 10% 2	4361
	21st to end	Night	27% 12% 24% 26% 10% 1	4521
February	1st to 10th	Night	38% 12% 19% 22% 8% 1	2470
	11th to 20th	Night	35% 15% 19% 19% 11% 1	2403
	21st to end	Night	35% 9% 16% 21% 17% 2	1970
March	1st to 10th	Night	31% 12% 20% 23% 12% 2	1992
	11th to 20th	Night	26% 14% 20% 26% 11% 2	1980
	21st to end	Night	40% 11% 20% 21% 6% 1	2178
April	1st to 10th	Night	37% 10% 20% 20% 11% 2	1814
	11th to 20th	Night	44% 10% 18% 23% 6%	1705
	21st to end	Night	39% 12% 18% 23% 9%	1620
May	1st to 10th	Night	38% 11% 17% 24% 9% 1	1566
	11th to 20th	Night	37% 13% 19% 24% 7%	1418
	21st to end	Night	42% 16% 20% 16% 5%	1552
June	1st to 10th	Night	33% 13% 21% 22% 9% 1	1440
	11th to 20th	Night	31% 14% 17% 22% 13% 4	1274
	21st to end	Night	18% 10% 18% 31% 18% 6%	1260
July	1st to 10th	Night	16% 9% 16% 33% 23% 3	1225
	11th to 20th	Night	13% 10% 13% 24% 25% 14%	1362
	21st to end	Night	16% 7% 13% 22% 28% 14%	1564
August	1st to 10th	Night	25% 9% 14% 25% 18% 8%	1602
	11th to 20th	Night	18% 8% 13% 28% 23% 10%	1602
	21st to end	Night	23% 7% 12% 22% 26% 10%	1849
September	1st to 10th	Night	23% 6% 9% 22% 29% 12%	1800
	11th to 20th	Night	25% 7% 13% 26% 23% 6%	1880
	21st to end	Night	27% 6% 12% 28% 23% 4	2011
October	1st to 10th	Night	35% 9% 13% 25% 14% 3	2160
	11th to 20th	Night	31% 8% 15% 25% 17% 3	2160
	21st to end	Night	27% 11% 16% 27% 15% 3	2376
November	1st to 10th	Night	31% 11% 17% 25% 13% 3	2534
	11th to 20th	Night	28% 11% 22% 26% 12% 2	2660
	21st to end	Night	29% 11% 19% 24% 15% 2	2660
December	1st to 10th	Night	30% 15% 19% 22% 11% 3	2660
	11th to 20th	Night	23% 13% 24% 33% 8%	3272
	21st to end	Night	27% 11% 14% 27% 15% 6%	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	6% 22% 43% 26% 4	270
	11th to 20th	Day	5% 27% 44% 17% 6% 1	270
	21st to end	Day	6% 14% 60% 14% 4 1	297
February	1st to 10th	Day	7% 33% 49% 10% 2	270
	11th to 20th	Day	3 36% 43% 14% 3 1	270
	21st to end	Day	5% 27% 45% 21% 3	210
March	1st to 10th	Day	6% 23% 52% 16% 2 1	406
	11th to 20th	Day	5% 23% 47% 21% 4	420
	21st to end	Day	12% 22% 40% 22% 3 1	462
April	1st to 10th	Day	15% 26% 45% 12% 2	420
	11th to 20th	Day	14% 27% 42% 15% 1	412
	21st to end	Day	24% 16% 32% 20% 7% 1	420
May	1st to 10th	Day	15% 16% 32% 27% 9% 1	476
	11th to 20th	Day	16% 11% 33% 26% 12% 2	625
	21st to end	Day	19% 12% 25% 27% 13% 3	679
June	1st to 10th	Day	10% 10% 34% 29% 14% 3	630
	11th to 20th	Day	11% 18% 39% 23% 8% 1	630
	21st to end	Day	5% 7% 35% 35% 15% 2	630
July	1st to 10th	Day	4 6% 35% 36% 17% 2	621
	11th to 20th	Day	3 7% 36% 41% 13%	618
	21st to end	Day	3 5% 32% 40% 18% 1	602
August	1st to 10th	Day	6% 7% 38% 35% 12% 2	447
	11th to 20th	Day	5% 8% 30% 40% 16% 1	437
	21st to end	Day	4 12% 36% 33% 12% 4	495
September	1st to 10th	Day	6% 11% 38% 34% 11%	450
	11th to 20th	Day	12% 12% 36% 28% 11% 2	450
	21st to end	Day	11% 13% 39% 28% 7% 1	417
October	1st to 10th	Day	11% 13% 34% 30% 11% 1	270
	11th to 20th	Day	7% 24% 41% 19% 9%	270
	21st to end	Day	6% 28% 43% 18% 5%	297
November	1st to 10th	Day	6% 26% 47% 14% 6%	270
	11th to 20th	Day	6% 32% 45% 14% 3 1	270
	21st to end	Day	7% 28% 46% 17% 2	270
December	1st to 10th	Day	4 32% 44% 16% 3	270
	11th to 20th	Day	5% 32% 49% 13% 1	270
	21st to end	Day	7% 27% 45% 15% 6%	297
January	1st to 10th	Night	3 15% 55% 23% 3	950
	11th to 20th	Night	4 17% 56% 18% 5%	907
	21st to end	Night	5% 11% 57% 22% 5%	836
February	1st to 10th	Night	3 18% 53% 20% 5%	760
	11th to 20th	Night	4 13% 54% 22% 6% 1	744
	21st to end	Night	3 14% 50% 26% 6%	610
March	1st to 10th	Night	4 11% 54% 24% 7%	720
	11th to 20th	Night	7% 8% 49% 28% 8%	720
	21st to end	Night	8% 12% 43% 28% 7% 1	792
April	1st to 10th	Night	9% 14% 44% 28% 5%	554
	11th to 20th	Night	10% 16% 43% 25% 5%	533
	21st to end	Night	16% 7% 38% 29% 10% 1	540
May	1st to 10th	Night	14% 11% 30% 33% 12% 1	540
	11th to 20th	Night	14% 8% 27% 37% 14% 2	531
	21st to end	Night	17% 7% 28% 34% 13% 1	584
June	1st to 10th	Night	12% 6% 32% 32% 16% 1	540
	11th to 20th	Night	9% 8% 39% 36% 8% 1	374
	21st to end	Night	4 3 26% 50% 17% 1	360
July	1st to 10th	Night	3 1 21% 50% 25% 1	350
	11th to 20th	Night	2 4 31% 52% 11%	492
	21st to end	Night	3 2 29% 45% 20% 2	591
August	1st to 10th	Night	6% 2 23% 49% 19% 1	537
	11th to 20th	Night	4 3 22% 49% 19% 1	534
	21st to end	Night	6% 6% 24% 44% 17% 2	594
September	1st to 10th	Night	8% 5% 30% 41% 15% 3	540
	11th to 20th	Night	8% 4 30% 40% 15% 3	620
	21st to end	Night	11% 7% 34% 32% 15% 2	720
October	1st to 10th	Night	15% 6% 33% 33% 11% 2	720
	11th to 20th	Night	9% 9% 43% 28% 11% 1	720
	21st to end	Night	6% 11% 50% 24% 7% 1	792
November	1st to 10th	Night	7% 12% 56% 21% 5%	886
	11th to 20th	Night	6% 17% 57% 19% 2	950
	21st to end	Night	5% 13% 55% 23% 3	950
December	1st to 10th	Night	3 15% 54% 23% 5%	950
	11th to 20th	Night	4 13% 59% 21% 3 1	950
	21st to end	Night	4 18% 54% 19% 4 1	1045

Page generated at 2024-02-22 04:05:45. Version ac07

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