Beaverlodge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beaverlodge clear sky chart from 2005-11-06 to 2025-02-25.

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	10% 10% 4 9% 6% 5% 5% 4 6% 8% 33%	111585
	Night	8% 11% 4 10% 6% 6% 5% 4 6% 7% 31%	115715
Transparency	Day	47% 7% 14% 21% 9% 1	111308
	Night	50% 7% 14% 20% 9% 1	115638
Seeing	Day	15% 9% 24% 28% 18% 6%	16823
	Night	15% 8% 27% 32% 15% 2	25065

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	5% 14% 6% 14% 8% 6% 5% 5% 8% 9% 21%	2719
	11th to 20th	Day	6% 13% 3 10% 6% 8% 8% 6% 9% 8% 22%	2822
	21st to end	Day	7% 11% 5% 9% 6% 6% 6% 4 7% 8% 32%	3635
February	1st to 10th	Day	7% 13% 6% 11% 7% 7% 5% 5% 6% 9% 24%	1600
	11th to 20th	Day	5% 15% 6% 12% 6% 6% 7% 4 7% 7% 26%	1643
	21st to end	Day	5% 14% 6% 11% 8% 7% 6% 4 6% 6% 25%	1507
March	1st to 10th	Day	3 8% 4 15% 11% 9% 6% 4 6% 7% 26%	3138
	11th to 20th	Day	8% 12% 4 9% 5% 5% 5% 5% 6% 8% 33%	3290
	21st to end	Day	5% 13% 5% 14% 6% 5% 5% 4 7% 7% 29%	4150
April	1st to 10th	Day	4 11% 5% 11% 8% 6% 7% 5% 6% 8% 29%	2280
	11th to 20th	Day	8% 13% 5% 10% 6% 4 5% 5% 6% 7% 30%	2440
	21st to end	Day	10% 12% 4 10% 6% 5% 5% 4 6% 8% 29%	2660
May	1st to 10th	Day	8% 10% 4 10% 6% 6% 5% 5% 6% 7% 33%	4420
	11th to 20th	Day	8% 11% 4 9% 6% 6% 6% 5% 6% 8% 29%	4739
	21st to end	Day	14% 10% 4 9% 7% 6% 6% 4 6% 6% 27%	5509
June	1st to 10th	Day	14% 8% 4 7% 5% 6% 5% 4 6% 7% 33%	3040
	11th to 20th	Day	17% 10% 3 8% 6% 6% 6% 4 6% 6% 28%	3040
	21st to end	Day	12% 7% 3 8% 6% 5% 6% 4 7% 8% 35%	3040
July	1st to 10th	Day	13% 5% 2 5% 3 4 4 4 6% 7% 48%	5060
	11th to 20th	Day	8% 4 1 5% 4 4 5% 4 6% 8% 50%	5060
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 7% 8% 39%	5277
August	1st to 10th	Day	10% 6% 2 5% 5% 4 4 3 5% 7% 49%	4401
	11th to 20th	Day	12% 6% 2 7% 4 5% 5% 4 7% 9% 39%	4330
	21st to end	Day	14% 7% 3 6% 5% 4 5% 4 6% 8% 39%	4599
September	1st to 10th	Day	13% 7% 2 6% 5% 4 5% 4 5% 8% 41%	2280
	11th to 20th	Day	14% 8% 2 7% 5% 5% 4 3 5% 8% 39%	2267
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 9% 38%	2052
October	1st to 10th	Day	13% 10% 3 9% 5% 6% 5% 4 5% 8% 32%	3180
	11th to 20th	Day	11% 11% 3 10% 5% 5% 6% 5% 7% 7% 30%	2921
	21st to end	Day	10% 13% 4 9% 4 4 5% 4 7% 8% 32%	3008
November	1st to 10th	Day	13% 17% 4 9% 5% 5% 4 4 6% 7% 26%	1523
	11th to 20th	Day	12% 15% 5% 11% 6% 5% 4 4 5% 6% 27%	1400
	21st to end	Day	10% 14% 4 12% 8% 5% 5% 3 5% 8% 26%	1341
December	1st to 10th	Day	13% 19% 4 11% 8% 5% 6% 3 5% 5% 21%	1960
	11th to 20th	Day	10% 17% 5% 9% 8% 7% 5% 5% 6% 7% 20%	2262
	21st to end	Day	4 9% 4 10% 5% 4 5% 4 8% 9% 38%	2992
January	1st to 10th	Night	4 14% 6% 16% 8% 5% 5% 4 6% 7% 24%	7226
	11th to 20th	Night	5% 11% 5% 11% 8% 7% 7% 6% 9% 9% 23%	7104
	21st to end	Night	9% 16% 4 8% 4 6% 6% 4 6% 8% 29%	7320
February	1st to 10th	Night	8% 16% 6% 11% 7% 5% 5% 4 6% 7% 26%	2800
	11th to 20th	Night	6% 13% 5% 11% 6% 6% 6% 5% 6% 8% 27%	2642
	21st to end	Night	4 14% 5% 12% 7% 7% 7% 5% 5% 8% 27%	2040
March	1st to 10th	Night	2 10% 5% 16% 10% 8% 7% 4 6% 6% 26%	3736
	11th to 20th	Night	7% 13% 4 9% 5% 5% 5% 4 6% 10% 31%	3685
	21st to end	Night	5% 10% 5% 11% 6% 5% 4 4 6% 9% 36%	3503
April	1st to 10th	Night	5% 12% 5% 11% 7% 6% 7% 5% 7% 8% 28%	1900
	11th to 20th	Night	9% 10% 4 10% 5% 5% 6% 5% 6% 6% 33%	1686
	21st to end	Night	11% 11% 4 8% 5% 6% 6% 5% 6% 5% 33%	1520
May	1st to 10th	Night	9% 10% 3 10% 6% 6% 5% 5% 7% 6% 34%	2540
	11th to 20th	Night	9% 10% 4 8% 6% 6% 5% 5% 7% 8% 32%	2152
	21st to end	Night	11% 10% 4 11% 8% 5% 6% 5% 7% 8% 26%	2066
June	1st to 10th	Night	12% 8% 5% 9% 6% 5% 5% 3 6% 7% 35%	1140
	11th to 20th	Night	19% 8% 2 7% 6% 5% 6% 5% 8% 8% 26%	1140
	21st to end	Night	12% 6% 3 7% 6% 5% 5% 4 7% 9% 36%	1140
July	1st to 10th	Night	12% 4 2 5% 4 4 4 3 7% 7% 50%	1900
	11th to 20th	Night	8% 5% 2 5% 5% 6% 5% 4 8% 9% 44%	1900
	21st to end	Night	10% 5% 2 7% 5% 5% 6% 5% 7% 9% 38%	2272
August	1st to 10th	Night	8% 4 2 5% 4 4 4 4 6% 9% 50%	2529
	11th to 20th	Night	11% 5% 2 5% 5% 5% 5% 5% 6% 8% 43%	2497
	21st to end	Night	11% 6% 2 8% 5% 7% 6% 4 6% 8% 36%	3063
September	1st to 10th	Night	13% 6% 3 8% 5% 5% 5% 3 6% 6% 40%	1900
	11th to 20th	Night	12% 9% 2 6% 4 4 5% 4 5% 8% 42%	1913
	21st to end	Night	13% 8% 3 7% 4 6% 5% 4 6% 7% 37%	2126
October	1st to 10th	Night	11% 10% 3 9% 6% 5% 5% 4 6% 8% 32%	3800
	11th to 20th	Night	8% 7% 3 8% 5% 5% 6% 4 6% 9% 39%	4008
	21st to end	Night	9% 12% 4 10% 6% 6% 6% 4 6% 7% 30%	4543
November	1st to 10th	Night	13% 15% 4 9% 6% 5% 4 4 6% 7% 26%	2755
	11th to 20th	Night	10% 16% 6% 11% 6% 4 4 4 6% 6% 28%	3000
	21st to end	Night	9% 18% 5% 10% 7% 5% 5% 3 6% 6% 27%	3055
December	1st to 10th	Night	10% 13% 5% 11% 7% 6% 5% 4 5% 7% 28%	5220
	11th to 20th	Night	10% 18% 5% 13% 7% 6% 5% 3 4 6% 23%	5930
	21st to end	Night	4 12% 4 11% 6% 6% 6% 4 6% 7% 33%	7964

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	57% 5% 12% 15% 10% 1	2719
	11th to 20th	Day	54% 7% 13% 15% 10% 1	2840
	21st to end	Day	46% 9% 20% 16% 8%	3635
February	1st to 10th	Day	55% 8% 12% 11% 13% 1	1600
	11th to 20th	Day	56% 8% 13% 16% 8% 1	1651
	21st to end	Day	58% 6% 12% 17% 7% 1	1507
March	1st to 10th	Day	54% 7% 9% 19% 10%	3138
	11th to 20th	Day	46% 8% 11% 22% 13%	3290
	21st to end	Day	51% 9% 14% 18% 9%	4150
April	1st to 10th	Day	50% 8% 15% 18% 8% 1	2280
	11th to 20th	Day	52% 6% 13% 18% 10% 1	2440
	21st to end	Day	51% 8% 11% 22% 7% 1	2660
May	1st to 10th	Day	46% 7% 12% 22% 11% 1	4420
	11th to 20th	Day	48% 8% 12% 22% 10% 1	4743
	21st to end	Day	52% 9% 12% 18% 9% 1	5510
June	1st to 10th	Day	49% 7% 13% 20% 10% 1	3040
	11th to 20th	Day	55% 8% 10% 19% 9%	3040
	21st to end	Day	44% 9% 14% 22% 9% 1	3040
July	1st to 10th	Day	35% 6% 11% 24% 22% 2	4981
	11th to 20th	Day	32% 7% 14% 29% 16% 2	4973
	21st to end	Day	39% 8% 19% 25% 8% 1	5109
August	1st to 10th	Day	35% 7% 15% 34% 9%	4384
	11th to 20th	Day	39% 7% 17% 25% 12%	4372
	21st to end	Day	43% 7% 22% 24% 4	4598
September	1st to 10th	Day	41% 8% 19% 25% 6% 1	2280
	11th to 20th	Day	43% 7% 17% 25% 7%	2267
	21st to end	Day	42% 9% 15% 23% 10% 1	2052
October	1st to 10th	Day	51% 4 19% 20% 6%	3180
	11th to 20th	Day	51% 6% 14% 24% 5%	2921
	21st to end	Day	48% 6% 23% 19% 4	3008
November	1st to 10th	Day	56% 7% 11% 19% 6% 1	1523
	11th to 20th	Day	57% 6% 15% 15% 8%	1400
	21st to end	Day	57% 6% 12% 16% 7% 2	1341
December	1st to 10th	Day	65% 6% 13% 10% 6% 1	1960
	11th to 20th	Day	61% 8% 14% 13% 4	2264
	21st to end	Day	40% 7% 13% 29% 10% 1	2992
January	1st to 10th	Night	57% 5% 10% 16% 11% 1	7226
	11th to 20th	Night	55% 6% 13% 14% 12% 1	7148
	21st to end	Night	51% 8% 17% 14% 9%	7320
February	1st to 10th	Night	58% 5% 12% 13% 11%	2800
	11th to 20th	Night	54% 8% 11% 19% 7% 1	2644
	21st to end	Night	54% 7% 12% 19% 7% 1	2040
March	1st to 10th	Night	55% 7% 10% 17% 10% 1	3736
	11th to 20th	Night	45% 7% 17% 19% 11%	3686
	21st to end	Night	42% 9% 13% 25% 11%	3503
April	1st to 10th	Night	49% 7% 14% 19% 10% 1	1900
	11th to 20th	Night	48% 8% 12% 20% 11% 1	1686
	21st to end	Night	49% 8% 10% 22% 10% 1	1520
May	1st to 10th	Night	46% 6% 11% 22% 13% 1	2540
	11th to 20th	Night	43% 10% 11% 24% 11% 1	2152
	21st to end	Night	50% 10% 13% 18% 9% 1	2066
June	1st to 10th	Night	48% 7% 11% 23% 11% 1	1140
	11th to 20th	Night	51% 8% 14% 21% 6% 1	1140
	21st to end	Night	43% 8% 17% 21% 11%	1140
July	1st to 10th	Night	32% 6% 13% 30% 18% 1	1870
	11th to 20th	Night	35% 8% 15% 23% 20%	1864
	21st to end	Night	39% 9% 22% 24% 6%	2201
August	1st to 10th	Night	30% 8% 19% 37% 6%	2521
	11th to 20th	Night	37% 8% 14% 30% 11% 1	2521
	21st to end	Night	44% 7% 24% 20% 4 1	3063
September	1st to 10th	Night	43% 8% 17% 23% 7% 2	1900
	11th to 20th	Night	39% 7% 18% 28% 8%	1913
	21st to end	Night	44% 9% 13% 21% 12% 1	2126
October	1st to 10th	Night	50% 6% 16% 19% 8%	3800
	11th to 20th	Night	41% 6% 15% 31% 7%	4008
	21st to end	Night	51% 7% 17% 18% 6%	4543
November	1st to 10th	Night	57% 7% 12% 18% 5% 1	2755
	11th to 20th	Night	55% 8% 12% 16% 8%	3000
	21st to end	Night	57% 7% 12% 17% 6% 2	3055
December	1st to 10th	Night	56% 6% 15% 16% 7%	5220
	11th to 20th	Night	64% 5% 14% 12% 5%	5927
	21st to end	Night	48% 7% 13% 25% 6% 1	7964

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	13% 8% 18% 41% 17% 5%	200
	11th to 20th	Day	15% 10% 25% 31% 16% 4	200
	21st to end	Day	10% 11% 30% 33% 14% 3	220
February	1st to 10th	Day	10% 14% 20% 33% 19% 6%	200
	11th to 20th	Day	10% 13% 22% 30% 20% 5%	283
	21st to end	Day	11% 10% 25% 33% 18% 3	347
March	1st to 10th	Day	8% 10% 26% 29% 21% 5%	460
	11th to 20th	Day	12% 7% 27% 32% 16% 7%	460
	21st to end	Day	15% 9% 24% 25% 22% 4	506
April	1st to 10th	Day	7% 15% 31% 29% 12% 5%	460
	11th to 20th	Day	14% 11% 25% 31% 13% 7%	452
	21st to end	Day	18% 13% 27% 21% 17% 5%	460
May	1st to 10th	Day	17% 12% 28% 27% 12% 4	463
	11th to 20th	Day	15% 7% 20% 31% 21% 5%	693
	21st to end	Day	16% 7% 23% 26% 21% 7%	940
June	1st to 10th	Day	16% 12% 26% 28% 15% 3	870
	11th to 20th	Day	23% 8% 22% 23% 19% 5%	870
	21st to end	Day	16% 8% 22% 24% 21% 10%	870
July	1st to 10th	Day	16% 6% 21% 28% 23% 6%	856
	11th to 20th	Day	14% 6% 25% 27% 21% 8%	852
	21st to end	Day	13% 9% 22% 32% 17% 7%	825
August	1st to 10th	Day	15% 7% 17% 28% 20% 13%	487
	11th to 20th	Day	11% 12% 29% 23% 18% 8%	477
	21st to end	Day	18% 9% 28% 22% 16% 8%	539
September	1st to 10th	Day	18% 10% 23% 26% 17% 7%	490
	11th to 20th	Day	17% 9% 25% 25% 18% 6%	490
	21st to end	Day	16% 14% 33% 22% 12% 4	490
October	1st to 10th	Day	18% 13% 23% 26% 15% 5%	490
	11th to 20th	Day	21% 9% 25% 26% 14% 5%	353
	21st to end	Day	18% 10% 27% 25% 14% 6%	300
November	1st to 10th	Day	19% 12% 23% 29% 17% 2	200
	11th to 20th	Day	24% 7% 26% 28% 15% 2	200
	21st to end	Day	17% 10% 27% 33% 11% 3	200
December	1st to 10th	Day	11% 9% 30% 36% 11% 5%	200
	11th to 20th	Day	17% 12% 23% 28% 18% 3	200
	21st to end	Day	13% 6% 23% 31% 22% 4	220
January	1st to 10th	Night	14% 9% 26% 32% 16% 3	1100
	11th to 20th	Night	13% 12% 28% 31% 13% 2	1060
	21st to end	Night	18% 12% 31% 28% 10% 1	960
February	1st to 10th	Night	18% 11% 22% 28% 17% 5%	800
	11th to 20th	Night	12% 8% 27% 34% 16% 2	784
	21st to end	Night	9% 9% 24% 36% 17% 5%	646
March	1st to 10th	Night	8% 9% 28% 32% 19% 3	760
	11th to 20th	Night	14% 7% 27% 36% 14% 2	760
	21st to end	Night	13% 6% 23% 34% 21% 3	836
April	1st to 10th	Night	11% 8% 29% 34% 14% 3	760
	11th to 20th	Night	13% 8% 27% 34% 16% 2	558
	21st to end	Night	14% 11% 30% 28% 16% 1	380
May	1st to 10th	Night	15% 8% 27% 36% 12% 2	380
	11th to 20th	Night	14% 7% 27% 33% 16% 2	374
	21st to end	Night	14% 6% 25% 31% 21% 2	411
June	1st to 10th	Night	13% 10% 28% 30% 19%	380
	11th to 20th	Night	22% 5% 20% 33% 18% 3	380
	21st to end	Night	15% 3 26% 33% 21% 2	380
July	1st to 10th	Night	14% 3 20% 40% 21% 2	370
	11th to 20th	Night	15% 4 25% 30% 23% 3	368
	21st to end	Night	12% 2 22% 38% 23% 3	416
August	1st to 10th	Night	11% 4 20% 31% 30% 4	378
	11th to 20th	Night	7% 4 29% 35% 22% 3	376
	21st to end	Night	15% 6% 28% 29% 19% 2	570
September	1st to 10th	Night	16% 5% 24% 35% 18% 1	760
	11th to 20th	Night	16% 5% 23% 32% 21% 2	760
	21st to end	Night	17% 9% 30% 29% 13% 2	760
October	1st to 10th	Night	19% 7% 30% 31% 12% 1	760
	11th to 20th	Night	15% 8% 29% 36% 11% 2	760
	21st to end	Night	19% 12% 30% 29% 9% 1	836
November	1st to 10th	Night	19% 8% 29% 30% 13% 2	805
	11th to 20th	Night	15% 12% 35% 28% 8% 1	1000
	21st to end	Night	16% 11% 30% 30% 11% 2	1027
December	1st to 10th	Night	12% 10% 32% 33% 10% 2	1100
	11th to 20th	Night	15% 10% 27% 31% 14% 4	1100
	21st to end	Night	14% 8% 25% 35% 15% 2	1210

Page generated at 2025-02-22 04:51:33. Version ac07

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