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 2024-11-05.

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	8% 9% 3 9% 6% 5% 5% 4 6% 7% 38%	105411
	Night	8% 10% 4 9% 6% 5% 5% 4 6% 7% 37%	102234
Transparency	Day	43% 10% 14% 19% 10% 4	105167
	Night	46% 11% 14% 17% 9% 3	102124
Seeing	Day	14% 15% 24% 25% 17% 4	15229
	Night	16% 11% 19% 34% 18% 2	24394

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% 8% 20% 10% 6% 4 3 4 5% 9%	2226
	11th to 20th	Day	10% 17% 6% 13% 8% 8% 5% 4 5% 5% 19%	2516
	21st to end	Day	10% 19% 8% 22% 7% 5% 4 3 4 4 12%	2794
February	1st to 10th	Day	11% 20% 6% 13% 8% 5% 5% 4 6% 6% 15%	1577
	11th to 20th	Day	7% 16% 6% 13% 8% 5% 6% 5% 8% 7% 19%	1698
	21st to end	Day	8% 18% 6% 13% 8% 6% 6% 4 6% 5% 19%	1570
March	1st to 10th	Day	5% 14% 5% 11% 8% 6% 6% 5% 7% 9% 25%	3138
	11th to 20th	Day	4 13% 3 8% 6% 6% 6% 4 6% 8% 37%	3452
	21st to end	Day	8% 17% 5% 13% 8% 7% 6% 5% 7% 7% 17%	3874
April	1st to 10th	Day	9% 14% 5% 10% 8% 7% 6% 5% 7% 7% 23%	2285
	11th to 20th	Day	13% 12% 4 10% 6% 6% 6% 4 6% 6% 26%	2440
	21st to end	Day	13% 10% 3 11% 7% 5% 5% 4 7% 6% 27%	2470
May	1st to 10th	Day	14% 12% 4 10% 6% 5% 5% 4 5% 6% 29%	4110
	11th to 20th	Day	7% 8% 3 8% 6% 6% 6% 5% 7% 9% 34%	4507
	21st to end	Day	13% 9% 3 8% 6% 6% 7% 5% 6% 9% 28%	5161
June	1st to 10th	Day	17% 8% 3 7% 6% 5% 4 5% 6% 7% 32%	2850
	11th to 20th	Day	16% 7% 3 7% 6% 5% 6% 5% 7% 7% 30%	2850
	21st to end	Day	8% 4 2 5% 4 4 5% 5% 7% 9% 47%	2850
July	1st to 10th	Day	2 2 1 4 4 3 5% 3 5% 7% 64%	4740
	11th to 20th	Day	2 1 1 2 2 2 2 2 4 5% 78%	4650
	21st to end	Day	2 1 1 2 2 2 3 2 4 7% 74%	4790
August	1st to 10th	Day	5% 2 1 3 2 3 5% 4 6% 9% 59%	4320
	11th to 20th	Day	5% 3 1 4 3 3 4 3 6% 8% 60%	4028
	21st to end	Day	5% 3 2 4 3 4 4 4 5% 8% 58%	4521
September	1st to 10th	Day	6% 4 2 4 4 4 4 3 6% 7% 56%	2281
	11th to 20th	Day	8% 4 2 5% 5% 5% 6% 3 6% 8% 46%	2090
	21st to end	Day	8% 5% 2 6% 6% 5% 5% 5% 7% 7% 45%	2090
October	1st to 10th	Day	7% 5% 2 4 4 3 4 3 5% 6% 57%	3405
	11th to 20th	Day	8% 6% 2 7% 4 4 5% 4 6% 8% 45%	2966
	21st to end	Day	10% 12% 4 10% 6% 6% 6% 4 7% 8% 27%	3101
November	1st to 10th	Day	15% 16% 4 10% 6% 6% 5% 4 6% 7% 19%	1710
	11th to 20th	Day	10% 15% 5% 13% 7% 6% 6% 4 7% 6% 21%	1524
	21st to end	Day	9% 15% 5% 13% 9% 8% 4 4 6% 7% 20%	1373
December	1st to 10th	Day	9% 20% 7% 11% 8% 7% 5% 3 5% 5% 20%	1330
	11th to 20th	Day	8% 19% 7% 18% 9% 7% 5% 5% 5% 5% 11%	1682
	21st to end	Day	9% 16% 7% 20% 12% 8% 5% 3 5% 4 11%	2442
January	1st to 10th	Night	10% 22% 6% 18% 10% 7% 6% 3 4 5% 9%	4726
	11th to 20th	Night	9% 15% 6% 13% 7% 6% 6% 3 5% 5% 25%	4405
	21st to end	Night	12% 22% 9% 15% 6% 6% 4 3 4 5% 14%	4862
February	1st to 10th	Night	13% 15% 6% 11% 7% 5% 5% 4 5% 6% 23%	2602
	11th to 20th	Night	8% 16% 5% 11% 6% 4 5% 4 6% 7% 27%	2368
	21st to end	Night	5% 16% 5% 11% 7% 6% 6% 5% 6% 6% 27%	1884
March	1st to 10th	Night	5% 10% 3 9% 6% 6% 6% 5% 8% 9% 34%	3736
	11th to 20th	Night	4 9% 3 8% 6% 6% 5% 4 6% 8% 40%	3527
	21st to end	Night	9% 14% 5% 12% 8% 7% 7% 5% 7% 7% 21%	3777
April	1st to 10th	Night	7% 13% 3 8% 5% 5% 5% 4 6% 8% 36%	1895
	11th to 20th	Night	10% 9% 4 9% 6% 6% 5% 5% 6% 6% 35%	1691
	21st to end	Night	12% 8% 4 7% 5% 5% 5% 5% 5% 8% 38%	1710
May	1st to 10th	Night	14% 11% 4 7% 6% 5% 4 4 6% 7% 32%	2860
	11th to 20th	Night	7% 6% 3 7% 5% 4 5% 5% 7% 9% 41%	2384
	21st to end	Night	17% 10% 3 8% 5% 5% 6% 5% 5% 7% 29%	2414
June	1st to 10th	Night	13% 7% 3 6% 4 5% 5% 5% 5% 6% 40%	1330
	11th to 20th	Night	15% 5% 2 5% 5% 5% 5% 6% 6% 7% 38%	1330
	21st to end	Night	4 4 2 4 4 5% 4 4 6% 6% 57%	1330
July	1st to 10th	Night	2 1 1 3 2 3 3 2 4 7% 71%	2220
	11th to 20th	Night	2 2 1 2 1 2 2 2 2 4 80%	2306
	21st to end	Night	2 1 1 2 2 2 2 2 4 5% 77%	2762
August	1st to 10th	Night	4 3 1 3 2 2 3 1 5% 8% 69%	2612
	11th to 20th	Night	4 2 1 5% 4 4 5% 4 7% 9% 58%	2811
	21st to end	Night	4 2 1 3 2 3 3 3 6% 6% 67%	3146
September	1st to 10th	Night	5% 2 1 5% 3 4 4 3 6% 7% 60%	1896
	11th to 20th	Night	7% 4 2 6% 4 4 3 4 6% 7% 53%	2090
	21st to end	Night	7% 4 2 6% 4 4 4 4 6% 8% 52%	2090
October	1st to 10th	Night	5% 4 2 4 4 4 4 3 6% 9% 56%	3571
	11th to 20th	Night	5% 4 2 4 4 5% 5% 4 7% 9% 51%	3957
	21st to end	Night	7% 7% 3 6% 5% 4 5% 5% 6% 9% 44%	4457
November	1st to 10th	Night	13% 14% 4 9% 6% 6% 5% 4 6% 8% 25%	2469
	11th to 20th	Night	9% 14% 4 10% 7% 6% 6% 4 6% 7% 27%	2636
	21st to end	Night	9% 16% 5% 9% 8% 5% 5% 4 6% 6% 26%	2806
December	1st to 10th	Night	9% 17% 6% 11% 7% 7% 5% 4 6% 6% 22%	2850
	11th to 20th	Night	10% 17% 7% 14% 10% 7% 5% 4 5% 5% 17%	3510
	21st to end	Night	10% 17% 7% 17% 9% 7% 5% 3 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% 2	2285
	11th to 20th	Day	55% 11% 13% 17% 5%	2440
	21st to end	Day	53% 12% 14% 16% 5% 1	2470
May	1st to 10th	Day	53% 9% 13% 20% 5%	4110
	11th to 20th	Day	34% 18% 21% 20% 7%	4511
	21st to end	Day	45% 17% 19% 15% 4	5162
June	1st to 10th	Day	49% 10% 16% 18% 7%	2850
	11th to 20th	Day	49% 11% 14% 17% 7% 2	2850
	21st to end	Day	30% 10% 18% 25% 15% 1	2850
July	1st to 10th	Day	19% 7% 9% 26% 25% 13%	4666
	11th to 20th	Day	10% 4 7% 14% 27% 37%	4569
	21st to end	Day	11% 3 7% 22% 35% 21%	4639
August	1st to 10th	Day	20% 6% 12% 31% 25% 7%	4303
	11th to 20th	Day	21% 8% 15% 36% 19% 2	4067
	21st to end	Day	23% 7% 14% 34% 19% 2	4520
September	1st to 10th	Day	26% 7% 13% 30% 18% 6%	2281
	11th to 20th	Day	34% 10% 16% 24% 14% 1	2090
	21st to end	Day	36% 11% 20% 23% 10% 1	2090
October	1st to 10th	Day	27% 7% 18% 37% 11%	3405
	11th to 20th	Day	37% 9% 23% 25% 6%	2966
	21st to end	Day	53% 11% 17% 17% 3	3101
November	1st to 10th	Day	65% 11% 13% 8% 3	1710
	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	48% 11% 15% 18% 7% 1	1691
	21st to end	Night	45% 11% 18% 19% 6% 1	1710
May	1st to 10th	Night	49% 12% 12% 20% 7%	2860
	11th to 20th	Night	35% 14% 16% 26% 10%	2384
	21st to end	Night	49% 13% 18% 14% 5%	2414
June	1st to 10th	Night	43% 9% 16% 22% 9%	1330
	11th to 20th	Night	44% 12% 14% 21% 8% 2	1330
	21st to end	Night	27% 8% 15% 29% 18% 2	1330
July	1st to 10th	Night	15% 5% 11% 28% 28% 14%	2185
	11th to 20th	Night	11% 3 7% 16% 22% 42%	2264
	21st to end	Night	11% 4 8% 21% 29% 27%	2674
August	1st to 10th	Night	16% 4 10% 33% 27% 11%	2604
	11th to 20th	Night	23% 7% 14% 34% 18% 4	2838
	21st to end	Night	17% 5% 13% 37% 23% 5%	3146
September	1st to 10th	Night	22% 7% 15% 30% 19% 8%	1896
	11th to 20th	Night	29% 8% 14% 29% 17% 2	2090
	21st to end	Night	31% 9% 21% 22% 14% 3	2090
October	1st to 10th	Night	27% 7% 18% 34% 14%	3571
	11th to 20th	Night	28% 10% 24% 27% 12%	3957
	21st to end	Night	38% 11% 22% 22% 7%	4457
November	1st to 10th	Night	59% 12% 15% 10% 4	2469
	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% 26% 22% 8% 2	460
	11th to 20th	Day	19% 22% 28% 18% 11% 2	452
	21st to end	Day	16% 23% 26% 21% 12% 2	460
May	1st to 10th	Day	16% 15% 25% 27% 15% 2	463
	11th to 20th	Day	19% 11% 22% 26% 18% 4	567
	21st to end	Day	20% 14% 16% 26% 19% 5%	734
June	1st to 10th	Day	16% 14% 24% 24% 18% 4	680
	11th to 20th	Day	17% 18% 28% 21% 14% 2	680
	21st to end	Day	9% 10% 24% 26% 26% 5%	680
July	1st to 10th	Day	4 6% 25% 30% 29% 5%	671
	11th to 20th	Day	5% 10% 25% 33% 24% 4	617
	21st to end	Day	3 8% 24% 36% 24% 5%	531
August	1st to 10th	Day	6% 9% 25% 32% 22% 6%	487
	11th to 20th	Day	5% 7% 22% 34% 24% 8%	477
	21st to end	Day	8% 10% 25% 29% 22% 6%	539
September	1st to 10th	Day	8% 10% 29% 25% 21% 7%	490
	11th to 20th	Day	9% 13% 25% 26% 19% 8%	490
	21st to end	Day	12% 16% 28% 24% 16% 6%	490
October	1st to 10th	Day	15% 11% 26% 25% 16% 7%	444
	11th to 20th	Day	15% 15% 22% 23% 17% 8%	300
	21st to end	Day	25% 20% 18% 23% 12% 2	330
November	1st to 10th	Day	26% 19% 22% 21% 12%	282
	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% 21% 34% 15% 1	755
	11th to 20th	Night	14% 13% 28% 32% 12%	563
	21st to end	Night	16% 11% 26% 30% 15% 1	570
May	1st to 10th	Night	10% 12% 23% 36% 19% 1	570
	11th to 20th	Night	12% 5% 18% 37% 27% 1	386
	21st to end	Night	19% 7% 17% 28% 27% 3	411
June	1st to 10th	Night	16% 8% 18% 34% 21% 4	380
	11th to 20th	Night	16% 10% 23% 29% 21% 1	380
	21st to end	Night	7% 4 16% 42% 29% 3	380
July	1st to 10th	Night	3 2 11% 45% 37% 2	370
	11th to 20th	Night	4 3 12% 53% 27% 1	368
	21st to end	Night	3 2 11% 45% 38% 2	416
August	1st to 10th	Night	5% 4 9% 40% 40% 3	422
	11th to 20th	Night	5% 2 11% 40% 36% 6%	564
	21st to end	Night	7% 4 14% 41% 34% 1	627
September	1st to 10th	Night	6% 4 13% 43% 31% 4	731
	11th to 20th	Night	10% 4 12% 35% 34% 5%	760
	21st to end	Night	11% 7% 14% 37% 27% 4	760
October	1st to 10th	Night	11% 8% 16% 42% 21% 2	760
	11th to 20th	Night	12% 9% 18% 36% 22% 3	760
	21st to end	Night	19% 11% 23% 32% 15% 1	836
November	1st to 10th	Night	23% 15% 21% 32% 9% 1	760
	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 2024-11-03 00:11:11. Version ac07

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