Kalispell
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kalispell clear sky chart from 2005-11-06 to 2024-04-10.

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	9% 10% 4 8% 7% 4 5% 5% 6% 7% 34%	82652
	Night	9% 11% 5% 8% 7% 4 5% 5% 5% 7% 34%	86147
Transparency	Day	48% 11% 14% 17% 9% 2	82369
	Night	50% 12% 13% 15% 8% 2	86010
Seeing	Day	14% 15% 24% 25% 17% 4	14359
	Night	16% 12% 19% 33% 18% 2	23791

By Month

Percentage Cloud Cover NW (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	9% 22% 9% 17% 12% 4 5% 4 4 5% 9%	2226
	11th to 20th	Day	10% 16% 6% 11% 9% 6% 7% 5% 5% 6% 19%	2516
	21st to end	Day	11% 19% 9% 20% 10% 4 4 4 4 4 12%	2794
February	1st to 10th	Day	12% 19% 7% 12% 9% 5% 5% 6% 5% 6% 16%	1577
	11th to 20th	Day	7% 15% 6% 12% 9% 4 7% 6% 8% 7% 19%	1698
	21st to end	Day	8% 17% 7% 12% 9% 4 7% 6% 6% 5% 19%	1570
March	1st to 10th	Day	5% 13% 6% 10% 9% 4 6% 6% 6% 9% 25%	3138
	11th to 20th	Day	4 12% 4 7% 8% 4 6% 5% 6% 8% 37%	3452
	21st to end	Day	8% 16% 6% 11% 9% 5% 7% 7% 7% 7% 17%	3874
April	1st to 10th	Day	9% 12% 6% 9% 8% 6% 6% 6% 7% 7% 23%	2274
	11th to 20th	Day	14% 12% 5% 10% 7% 5% 6% 6% 6% 6% 26%	2310
	21st to end	Day	14% 9% 4 9% 8% 4 6% 6% 6% 6% 28%	2340
May	1st to 10th	Day	11% 8% 3 7% 7% 4 6% 6% 6% 7% 35%	2340
	11th to 20th	Day	11% 8% 4 7% 7% 4 6% 7% 6% 8% 34%	2537
	21st to end	Day	19% 9% 4 7% 7% 4 6% 5% 5% 7% 26%	2917
June	1st to 10th	Day	18% 7% 4 6% 7% 4 5% 5% 6% 7% 31%	2700
	11th to 20th	Day	17% 6% 3 7% 7% 4 7% 7% 6% 8% 29%	2700
	21st to end	Day	8% 4 2 4 5% 3 5% 6% 7% 10% 47%	2700
July	1st to 10th	Day	4 2 1 3 4 2 5% 5% 5% 7% 61%	2700
	11th to 20th	Day	4 2 2 2 3 2 3 4 5% 7% 65%	2652
	21st to end	Day	2 1 1 2 2 2 2 3 4 6% 73%	2741
August	1st to 10th	Day	5% 2 1 3 2 2 4 5% 6% 8% 62%	2465
	11th to 20th	Day	6% 3 1 3 3 1 4 4 5% 7% 62%	2299
	21st to end	Day	6% 3 2 4 5% 3 4 5% 6% 8% 53%	2574
September	1st to 10th	Day	6% 4 2 4 5% 3 4 5% 6% 7% 55%	2162
	11th to 20th	Day	8% 4 3 4 5% 4 6% 5% 6% 8% 48%	1980
	21st to end	Day	8% 5% 2 5% 6% 4 6% 6% 7% 7% 44%	1980
October	1st to 10th	Day	12% 7% 3 6% 7% 3 5% 5% 6% 7% 38%	1937
	11th to 20th	Day	9% 8% 3 8% 7% 4 5% 5% 6% 8% 35%	1692
	21st to end	Day	12% 11% 4 10% 7% 4 5% 5% 6% 7% 28%	1782
November	1st to 10th	Day	16% 15% 5% 9% 8% 4 5% 5% 6% 7% 20%	1674
	11th to 20th	Day	10% 13% 6% 12% 8% 5% 6% 5% 7% 6% 22%	1524
	21st to end	Day	10% 14% 5% 11% 10% 6% 5% 5% 6% 7% 20%	1373
December	1st to 10th	Day	9% 19% 7% 10% 9% 5% 6% 4 4 5% 21%	1330
	11th to 20th	Day	8% 18% 7% 16% 11% 6% 6% 6% 5% 5% 12%	1682
	21st to end	Day	10% 15% 7% 18% 14% 6% 5% 4 5% 4 11%	2442
January	1st to 10th	Night	10% 21% 7% 15% 13% 5% 6% 5% 4 5% 9%	4726
	11th to 20th	Night	9% 14% 6% 12% 9% 5% 6% 5% 5% 6% 25%	4405
	21st to end	Night	12% 21% 10% 13% 8% 4 5% 4 4 5% 14%	4862
February	1st to 10th	Night	13% 14% 7% 9% 8% 4 6% 5% 5% 6% 23%	2602
	11th to 20th	Night	8% 16% 6% 9% 7% 3 5% 5% 6% 7% 27%	2368
	21st to end	Night	6% 14% 6% 10% 9% 4 6% 6% 6% 6% 27%	1884
March	1st to 10th	Night	5% 9% 3 8% 7% 4 6% 6% 8% 9% 34%	3736
	11th to 20th	Night	4 8% 4 7% 7% 4 6% 5% 6% 8% 40%	3527
	21st to end	Night	9% 14% 5% 11% 9% 5% 7% 6% 7% 7% 21%	3777
April	1st to 10th	Night	8% 10% 4 8% 6% 3 6% 5% 5% 8% 36%	1895
	11th to 20th	Night	10% 9% 4 8% 7% 4 6% 6% 6% 6% 35%	1601
	21st to end	Night	12% 7% 4 7% 5% 3 5% 5% 5% 9% 38%	1620
May	1st to 10th	Night	7% 7% 3 6% 7% 4 5% 5% 8% 9% 38%	1620
	11th to 20th	Night	10% 6% 3 5% 6% 3 6% 6% 6% 8% 41%	1354
	21st to end	Night	15% 9% 4 6% 6% 3 6% 5% 5% 8% 34%	1358
June	1st to 10th	Night	14% 6% 4 5% 5% 3 5% 6% 5% 6% 40%	1260
	11th to 20th	Night	16% 5% 2 5% 5% 4 5% 7% 7% 7% 38%	1260
	21st to end	Night	5% 3 2 4 4 3 4 5% 6% 7% 57%	1260
July	1st to 10th	Night	3 1 2 2 2 3 3 5% 8% 71%	1260
	11th to 20th	Night	4 2 1 2 2 1 3 2 4 6% 74%	1304
	21st to end	Night	2 1 1 2 2 1 2 3 4 6% 75%	1576
August	1st to 10th	Night	4 3 1 2 2 1 3 2 4 8% 70%	1473
	11th to 20th	Night	5% 1 1 2 2 2 3 5% 6% 8% 65%	1602
	21st to end	Night	6% 3 2 3 3 3 4 4 6% 6% 60%	1782
September	1st to 10th	Night	6% 2 2 4 4 3 4 4 6% 7% 60%	1795
	11th to 20th	Night	7% 4 2 5% 4 3 4 4 6% 7% 55%	1980
	21st to end	Night	8% 4 2 5% 5% 3 5% 4 6% 9% 50%	1980
October	1st to 10th	Night	9% 6% 3 5% 6% 3 5% 4 5% 7% 46%	2022
	11th to 20th	Night	8% 5% 3 5% 5% 5% 6% 5% 6% 8% 43%	2263
	21st to end	Night	11% 9% 3 8% 7% 4 5% 5% 4 7% 36%	2574
November	1st to 10th	Night	13% 12% 5% 7% 7% 4 6% 5% 6% 8% 26%	2405
	11th to 20th	Night	10% 13% 5% 9% 8% 4 6% 5% 6% 7% 27%	2636
	21st to end	Night	9% 14% 6% 8% 9% 4 6% 6% 6% 7% 26%	2806
December	1st to 10th	Night	9% 16% 7% 10% 8% 5% 6% 5% 6% 6% 22%	2850
	11th to 20th	Night	10% 16% 8% 13% 11% 6% 5% 5% 5% 5% 17%	3510
	21st to end	Night	10% 16% 7% 14% 11% 5% 5% 4 5% 6% 15%	5214

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	81% 10% 6% 2	2226
	11th to 20th	Day	68% 10% 10% 9% 3	2540
	21st to end	Day	75% 10% 8% 6% 1	2794
February	1st to 10th	Day	71% 10% 10% 6% 3 1	1577
	11th to 20th	Day	61% 17% 11% 7% 3	1707
	21st to end	Day	66% 11% 9% 9% 5% 1	1570
March	1st to 10th	Day	49% 15% 16% 14% 6%	3138
	11th to 20th	Day	40% 16% 25% 17% 2	3453
	21st to end	Day	60% 16% 13% 9% 3	3874
April	1st to 10th	Day	57% 12% 14% 14% 3	2274
	11th to 20th	Day	57% 10% 12% 16% 5%	2310
	21st to end	Day	53% 11% 14% 16% 4 1	2340
May	1st to 10th	Day	44% 10% 18% 21% 6%	2340
	11th to 20th	Day	43% 13% 19% 18% 7%	2541
	21st to end	Day	53% 10% 18% 13% 4	2918
June	1st to 10th	Day	50% 10% 16% 18% 6%	2700
	11th to 20th	Day	50% 11% 14% 18% 6% 1	2700
	21st to end	Day	30% 10% 18% 26% 15% 1	2700
July	1st to 10th	Day	21% 7% 12% 30% 23% 7%	2626
	11th to 20th	Day	18% 7% 12% 25% 29% 9%	2571
	21st to end	Day	12% 4 8% 27% 39% 9%	2589
August	1st to 10th	Day	19% 7% 13% 28% 25% 8%	2448
	11th to 20th	Day	20% 7% 14% 31% 24% 3	2299
	21st to end	Day	27% 8% 13% 28% 21% 4	2574
September	1st to 10th	Day	27% 8% 13% 29% 18% 5%	2162
	11th to 20th	Day	33% 10% 16% 24% 15% 2	1980
	21st to end	Day	38% 11% 19% 22% 9% 1	1980
October	1st to 10th	Day	43% 11% 17% 24% 5%	1937
	11th to 20th	Day	47% 10% 20% 18% 5%	1692
	21st to end	Day	55% 11% 16% 15% 3	1782
November	1st to 10th	Day	65% 11% 13% 8% 3	1674
	11th to 20th	Day	63% 14% 14% 5% 4	1524
	21st to end	Day	64% 15% 12% 7% 2	1373
December	1st to 10th	Day	69% 11% 12% 6% 2	1330
	11th to 20th	Day	75% 10% 11% 3 1	1684
	21st to end	Day	73% 13% 7% 6% 1	2442
January	1st to 10th	Night	79% 12% 4 4 1	4726
	11th to 20th	Night	61% 11% 10% 10% 5% 2	4443
	21st to end	Night	74% 11% 7% 5% 2	4862
February	1st to 10th	Night	63% 13% 12% 9% 3 1	2602
	11th to 20th	Night	58% 14% 15% 9% 3	2369
	21st to end	Night	58% 13% 12% 13% 4 1	1884
March	1st to 10th	Night	42% 17% 16% 17% 7%	3736
	11th to 20th	Night	39% 13% 23% 23% 2	3527
	21st to end	Night	58% 17% 14% 9% 2	3777
April	1st to 10th	Night	46% 15% 17% 19% 3	1895
	11th to 20th	Night	49% 11% 14% 18% 7% 1	1601
	21st to end	Night	44% 11% 18% 19% 6% 1	1620
May	1st to 10th	Night	40% 14% 16% 22% 8%	1620
	11th to 20th	Night	38% 12% 17% 23% 9%	1354
	21st to end	Night	49% 10% 19% 16% 7%	1358
June	1st to 10th	Night	44% 10% 16% 21% 9%	1260
	11th to 20th	Night	45% 12% 14% 21% 7% 1	1260
	21st to end	Night	27% 8% 16% 30% 18% 2	1260
July	1st to 10th	Night	14% 5% 11% 32% 29% 9%	1225
	11th to 20th	Night	14% 4 11% 27% 30% 13%	1262
	21st to end	Night	10% 5% 8% 24% 37% 15%	1488
August	1st to 10th	Night	15% 4 12% 31% 27% 11%	1465
	11th to 20th	Night	16% 7% 12% 34% 24% 6%	1602
	21st to end	Night	23% 7% 12% 28% 26% 5%	1782
September	1st to 10th	Night	23% 7% 15% 28% 19% 7%	1795
	11th to 20th	Night	28% 8% 13% 30% 18% 3	1980
	21st to end	Night	32% 9% 21% 22% 13% 3	1980
October	1st to 10th	Night	38% 11% 16% 26% 9%	2022
	11th to 20th	Night	39% 12% 19% 23% 7%	2263
	21st to end	Night	48% 12% 16% 17% 7%	2574
November	1st to 10th	Night	59% 12% 14% 10% 4	2405
	11th to 20th	Night	58% 14% 17% 8% 3	2636
	21st to end	Night	58% 14% 16% 9% 2	2806
December	1st to 10th	Night	65% 12% 13% 9% 2	2850
	11th to 20th	Night	70% 13% 12% 5% 1	3507
	21st to end	Night	69% 15% 9% 6% 1	5214

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% 18% 18% 24% 13% 6%	180
	11th to 20th	Day	23% 17% 23% 19% 9% 8%	180
	21st to end	Day	18% 18% 26% 27% 9% 3	198
February	1st to 10th	Day	23% 24% 24% 24% 5%	207
	11th to 20th	Day	15% 26% 22% 26% 9% 1	303
	21st to end	Day	22% 18% 27% 21% 10% 2	382
March	1st to 10th	Day	16% 24% 27% 21% 11% 1	460
	11th to 20th	Day	17% 17% 22% 23% 16% 5%	460
	21st to end	Day	16% 22% 28% 24% 9% 2	506
April	1st to 10th	Day	18% 25% 27% 22% 7% 2	457
	11th to 20th	Day	20% 24% 28% 16% 11% 1	412
	21st to end	Day	16% 23% 26% 21% 12% 2	420
May	1st to 10th	Day	14% 15% 26% 27% 15% 2	423
	11th to 20th	Day	19% 11% 21% 26% 19% 4	522
	21st to end	Day	21% 12% 15% 27% 20% 5%	679
June	1st to 10th	Day	16% 14% 24% 23% 19% 4	630
	11th to 20th	Day	17% 18% 27% 21% 14% 2	630
	21st to end	Day	9% 9% 23% 26% 27% 5%	630
July	1st to 10th	Day	4 6% 25% 30% 29% 6%	621
	11th to 20th	Day	5% 10% 25% 32% 24% 3	570
	21st to end	Day	2 8% 24% 36% 24% 6%	487
August	1st to 10th	Day	6% 9% 26% 32% 23% 6%	447
	11th to 20th	Day	5% 7% 23% 31% 25% 8%	437
	21st to end	Day	7% 10% 25% 30% 22% 6%	495
September	1st to 10th	Day	9% 11% 30% 25% 20% 6%	450
	11th to 20th	Day	9% 13% 24% 27% 18% 8%	450
	21st to end	Day	12% 16% 27% 24% 16% 6%	450
October	1st to 10th	Day	16% 11% 24% 26% 17% 7%	407
	11th to 20th	Day	16% 16% 22% 22% 17% 7%	270
	21st to end	Day	26% 20% 18% 22% 12% 2	297
November	1st to 10th	Day	27% 18% 22% 21% 12%	270
	11th to 20th	Day	20% 21% 21% 24% 11% 1	270
	21st to end	Day	17% 18% 22% 22% 17% 2	201
December	1st to 10th	Day	25% 23% 14% 17% 16% 5%	180
	11th to 20th	Day	23% 20% 20% 27% 9% 1	180
	21st to end	Day	18% 18% 28% 24% 9% 3	198
January	1st to 10th	Night	26% 16% 23% 23% 10% 1	950
	11th to 20th	Night	22% 15% 21% 28% 12% 2	770
	21st to end	Night	21% 14% 22% 32% 9% 1	836
February	1st to 10th	Night	21% 17% 22% 29% 9% 1	760
	11th to 20th	Night	20% 18% 22% 30% 9% 1	744
	21st to end	Night	16% 15% 25% 30% 13% 1	628
March	1st to 10th	Night	16% 14% 23% 33% 13% 1	760
	11th to 20th	Night	13% 16% 21% 32% 17% 1	760
	21st to end	Night	15% 15% 22% 32% 14% 2	836
April	1st to 10th	Night	16% 13% 22% 34% 15% 1	755
	11th to 20th	Night	15% 13% 28% 31% 13%	533
	21st to end	Night	17% 10% 26% 30% 16% 1	540
May	1st to 10th	Night	8% 12% 23% 36% 19% 1	540
	11th to 20th	Night	13% 5% 16% 37% 28% 1	366
	21st to end	Night	19% 6% 16% 28% 28% 3	389
June	1st to 10th	Night	15% 8% 18% 34% 22% 4	360
	11th to 20th	Night	17% 10% 23% 29% 21% 1	360
	21st to end	Night	7% 3 15% 41% 31% 3	360
July	1st to 10th	Night	3 3 11% 44% 38% 2	350
	11th to 20th	Night	5% 3 12% 51% 27% 1	348
	21st to end	Night	3 1 11% 45% 38% 2	394
August	1st to 10th	Night	5% 4 8% 39% 42% 3	399
	11th to 20th	Night	5% 2 11% 39% 37% 6%	534
	21st to end	Night	7% 4 13% 41% 35% 1	594
September	1st to 10th	Night	6% 4 13% 43% 31% 4	692
	11th to 20th	Night	9% 4 12% 34% 35% 6%	720
	21st to end	Night	11% 7% 13% 37% 28% 4	720
October	1st to 10th	Night	12% 8% 16% 41% 21% 2	720
	11th to 20th	Night	13% 10% 17% 36% 22% 3	720
	21st to end	Night	20% 11% 22% 31% 15% 1	792
November	1st to 10th	Night	24% 15% 20% 31% 9% 1	740
	11th to 20th	Night	24% 17% 21% 27% 11%	926
	21st to end	Night	19% 15% 19% 33% 13% 1	950
December	1st to 10th	Night	20% 14% 19% 30% 15% 2	950
	11th to 20th	Night	21% 15% 21% 33% 9% 1	950
	21st to end	Night	24% 15% 23% 28% 10% 1	1045

Page generated at 2024-04-07 07:28:12. Version ac07

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