Bonnyville
Clear Sky Chart
History

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

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	10% 9% 3 9% 6% 5% 5% 4 6% 8% 34%	105570
	Night	8% 10% 4 9% 6% 6% 6% 4 6% 8% 33%	102126
Transparency	Day	45% 8% 18% 22% 6%	105311
	Night	47% 8% 16% 21% 7% 1	102031
Seeing	Day	14% 6% 23% 30% 20% 7%	15621
	Night	13% 5% 25% 37% 17% 3	24620

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% 13% 6% 17% 10% 7% 6% 4 5% 5% 20%	2219
	11th to 20th	Day	5% 8% 3 9% 8% 7% 10% 6% 10% 10% 23%	2199
	21st to end	Day	6% 14% 6% 13% 7% 5% 5% 4 5% 6% 29%	2442
February	1st to 10th	Day	7% 12% 6% 13% 7% 6% 6% 6% 8% 7% 23%	1519
	11th to 20th	Day	7% 11% 4 12% 8% 7% 7% 5% 7% 9% 24%	1665
	21st to end	Day	5% 12% 5% 13% 9% 6% 7% 5% 7% 8% 24%	1413
March	1st to 10th	Day	5% 9% 4 9% 6% 6% 7% 7% 8% 9% 29%	3146
	11th to 20th	Day	4 9% 3 8% 6% 6% 6% 6% 8% 11% 32%	3489
	21st to end	Day	8% 13% 4 11% 6% 6% 5% 4 5% 6% 31%	3825
April	1st to 10th	Day	8% 11% 4 9% 6% 5% 6% 4 6% 8% 32%	2393
	11th to 20th	Day	13% 10% 3 10% 5% 6% 5% 5% 5% 7% 31%	2440
	21st to end	Day	13% 12% 3 8% 5% 5% 4 4 6% 8% 32%	2554
May	1st to 10th	Day	16% 10% 4 9% 6% 6% 6% 4 6% 6% 28%	4549
	11th to 20th	Day	16% 11% 3 8% 5% 5% 5% 4 6% 6% 32%	4694
	21st to end	Day	13% 8% 3 9% 6% 6% 6% 5% 7% 9% 29%	5161
June	1st to 10th	Day	16% 8% 3 8% 5% 6% 5% 4 7% 8% 30%	3004
	11th to 20th	Day	19% 9% 3 8% 6% 5% 5% 4 6% 8% 26%	3040
	21st to end	Day	12% 8% 2 8% 5% 5% 5% 5% 7% 8% 33%	3040
July	1st to 10th	Day	7% 5% 2 6% 5% 5% 5% 4 6% 10% 45%	4783
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 47%	4740
	21st to end	Day	12% 5% 2 5% 4 4 5% 4 7% 8% 43%	5138
August	1st to 10th	Day	12% 6% 2 6% 4 4 4 3 5% 7% 47%	4720
	11th to 20th	Day	8% 5% 3 7% 4 5% 6% 5% 7% 9% 42%	4077
	21st to end	Day	9% 5% 2 6% 4 4 5% 5% 6% 9% 45%	4521
September	1st to 10th	Day	11% 7% 2 6% 5% 4 4 4 7% 8% 43%	2380
	11th to 20th	Day	15% 7% 2 7% 4 4 3 3 6% 8% 40%	2173
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 5% 5% 9% 42%	2077
October	1st to 10th	Day	10% 9% 3 8% 5% 5% 4 4 7% 8% 37%	3170
	11th to 20th	Day	10% 10% 4 8% 5% 4 5% 3 6% 11% 36%	3042
	21st to end	Day	7% 12% 6% 11% 5% 5% 5% 4 6% 7% 31%	2859
November	1st to 10th	Day	11% 15% 4 10% 8% 7% 5% 4 6% 7% 23%	1560
	11th to 20th	Day	8% 14% 5% 13% 8% 7% 6% 3 6% 6% 24%	1444
	21st to end	Day	4 12% 6% 13% 8% 7% 4 4 5% 8% 28%	1301
December	1st to 10th	Day	6% 13% 5% 11% 9% 7% 6% 4 5% 8% 26%	1140
	11th to 20th	Day	6% 13% 5% 14% 7% 6% 4 4 7% 8% 26%	1439
	21st to end	Day	4 8% 3 9% 5% 5% 7% 5% 5% 7% 43%	2214
January	1st to 10th	Night	5% 11% 6% 18% 10% 8% 6% 4 6% 6% 20%	4726
	11th to 20th	Night	4 8% 4 11% 8% 8% 10% 5% 7% 9% 26%	4699
	21st to end	Night	6% 13% 5% 11% 8% 6% 5% 4 5% 7% 30%	5214
February	1st to 10th	Night	6% 11% 4 12% 9% 7% 5% 5% 6% 7% 26%	2676
	11th to 20th	Night	6% 11% 4 10% 7% 7% 5% 4 7% 7% 31%	2402
	21st to end	Night	4 8% 5% 11% 7% 7% 7% 5% 7% 7% 31%	2041
March	1st to 10th	Night	4 12% 5% 12% 6% 6% 6% 5% 7% 10% 26%	3724
	11th to 20th	Night	5% 10% 3 8% 6% 7% 6% 6% 9% 9% 33%	3490
	21st to end	Night	8% 14% 3 10% 7% 6% 5% 5% 6% 8% 28%	3828
April	1st to 10th	Night	7% 9% 3 9% 7% 5% 6% 5% 7% 9% 34%	1783
	11th to 20th	Night	10% 11% 3 10% 6% 6% 5% 4 5% 8% 32%	1691
	21st to end	Night	14% 10% 4 8% 4 5% 5% 4 5% 8% 33%	1625
May	1st to 10th	Night	17% 10% 3 8% 6% 5% 6% 4 6% 7% 29%	2414
	11th to 20th	Night	17% 9% 2 6% 5% 4 4 4 6% 7% 35%	2199
	21st to end	Night	11% 9% 3 9% 6% 6% 6% 5% 8% 8% 28%	2414
June	1st to 10th	Night	15% 7% 3 8% 5% 3 6% 5% 7% 7% 33%	1173
	11th to 20th	Night	16% 11% 3 7% 6% 6% 5% 5% 6% 8% 25%	1140
	21st to end	Night	13% 6% 2 7% 4 4 5% 5% 6% 9% 40%	1140
July	1st to 10th	Night	8% 5% 2 5% 3 4 5% 5% 7% 9% 46%	2174
	11th to 20th	Night	6% 4 1 4 4 4 4 4 7% 10% 50%	2220
	21st to end	Night	15% 5% 2 5% 3 3 4 4 6% 9% 44%	2414
August	1st to 10th	Night	13% 5% 2 6% 4 5% 5% 3 6% 8% 42%	2210
	11th to 20th	Night	8% 5% 2 6% 4 5% 6% 5% 7% 10% 41%	2759
	21st to end	Night	8% 5% 2 6% 4 4 4 4 7% 8% 47%	3146
September	1st to 10th	Night	13% 6% 2 6% 3 4 4 4 6% 8% 45%	1799
	11th to 20th	Night	12% 5% 2 6% 4 3 5% 4 6% 9% 44%	2004
	21st to end	Night	9% 5% 2 5% 5% 5% 4 5% 7% 8% 46%	2103
October	1st to 10th	Night	8% 7% 3 6% 4 5% 6% 4 7% 9% 40%	3800
	11th to 20th	Night	10% 8% 3 7% 5% 4 5% 4 7% 8% 40%	3886
	21st to end	Night	10% 11% 5% 11% 5% 5% 5% 5% 7% 8% 29%	4668
November	1st to 10th	Night	12% 16% 5% 9% 6% 6% 6% 4 5% 5% 27%	2723
	11th to 20th	Night	8% 14% 6% 13% 7% 6% 6% 5% 5% 7% 23%	2733
	21st to end	Night	5% 12% 5% 14% 7% 6% 5% 4 5% 7% 28%	2877
December	1st to 10th	Night	8% 12% 4 11% 7% 7% 6% 4 6% 8% 26%	3040
	11th to 20th	Night	8% 13% 5% 13% 9% 8% 6% 5% 6% 6% 21%	3753
	21st to end	Night	3 8% 3 9% 6% 6% 5% 4 6% 7% 42%	5438

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	63% 7% 11% 15% 4	2219
	11th to 20th	Day	51% 7% 17% 18% 5% 1	2220
	21st to end	Day	55% 8% 16% 14% 7%	2442
February	1st to 10th	Day	55% 8% 15% 14% 8%	1519
	11th to 20th	Day	53% 8% 16% 15% 7%	1674
	21st to end	Day	54% 8% 16% 16% 6%	1413
March	1st to 10th	Day	45% 9% 23% 19% 4	3146
	11th to 20th	Day	41% 10% 23% 21% 5%	3490
	21st to end	Day	50% 8% 13% 19% 10%	3825
April	1st to 10th	Day	48% 8% 17% 18% 9%	2393
	11th to 20th	Day	51% 6% 12% 21% 9% 1	2440
	21st to end	Day	49% 7% 14% 21% 8% 1	2554
May	1st to 10th	Day	54% 7% 12% 19% 7%	4549
	11th to 20th	Day	49% 8% 12% 21% 10% 1	4698
	21st to end	Day	47% 12% 16% 18% 7%	5162
June	1st to 10th	Day	48% 8% 15% 19% 8% 1	3004
	11th to 20th	Day	56% 9% 13% 17% 5% 1	3040
	21st to end	Day	44% 11% 17% 23% 5% 1	3040
July	1st to 10th	Day	33% 9% 23% 27% 7%	4709
	11th to 20th	Day	32% 8% 18% 28% 14%	4659
	21st to end	Day	37% 9% 22% 26% 5%	4976
August	1st to 10th	Day	37% 8% 21% 32% 2	4702
	11th to 20th	Day	36% 8% 23% 26% 6%	4117
	21st to end	Day	34% 8% 28% 28% 2	4520
September	1st to 10th	Day	38% 8% 20% 26% 7% 2	2380
	11th to 20th	Day	42% 7% 20% 26% 5%	2173
	21st to end	Day	39% 8% 17% 25% 10% 1	2077
October	1st to 10th	Day	43% 5% 22% 27% 3	3170
	11th to 20th	Day	44% 5% 17% 29% 6%	3042
	21st to end	Day	51% 6% 20% 20% 3	2859
November	1st to 10th	Day	59% 8% 13% 16% 4	1560
	11th to 20th	Day	59% 9% 15% 15% 3	1444
	21st to end	Day	54% 9% 17% 16% 4	1301
December	1st to 10th	Day	55% 8% 11% 19% 6% 1	1140
	11th to 20th	Day	56% 7% 16% 17% 5%	1440
	21st to end	Day	39% 6% 15% 28% 9% 1	2214
January	1st to 10th	Night	62% 8% 12% 13% 5% 1	4726
	11th to 20th	Night	51% 8% 15% 20% 6% 1	4740
	21st to end	Night	54% 8% 18% 15% 6%	5214
February	1st to 10th	Night	54% 7% 12% 18% 8%	2676
	11th to 20th	Night	48% 8% 14% 20% 10%	2403
	21st to end	Night	49% 8% 14% 19% 10% 1	2041
March	1st to 10th	Night	51% 8% 17% 20% 5%	3724
	11th to 20th	Night	42% 9% 19% 22% 6%	3490
	21st to end	Night	49% 9% 11% 21% 9%	3828
April	1st to 10th	Night	43% 7% 17% 20% 12% 1	1783
	11th to 20th	Night	48% 6% 12% 20% 11% 3	1691
	21st to end	Night	48% 6% 12% 21% 10% 3	1625
May	1st to 10th	Night	51% 7% 9% 23% 9% 1	2414
	11th to 20th	Night	44% 8% 12% 23% 12% 1	2199
	21st to end	Night	46% 12% 18% 16% 6% 1	2414
June	1st to 10th	Night	46% 9% 13% 22% 9% 1	1173
	11th to 20th	Night	55% 10% 14% 14% 7% 1	1140
	21st to end	Night	38% 11% 20% 23% 8% 1	1140
July	1st to 10th	Night	30% 10% 25% 25% 10% 1	2139
	11th to 20th	Night	27% 6% 17% 39% 10%	2178
	21st to end	Night	36% 8% 23% 27% 7%	2337
August	1st to 10th	Night	39% 7% 18% 33% 2	2203
	11th to 20th	Night	35% 9% 28% 21% 7%	2785
	21st to end	Night	33% 7% 24% 31% 4	3146
September	1st to 10th	Night	37% 7% 20% 26% 7% 3	1799
	11th to 20th	Night	37% 7% 20% 27% 9%	2004
	21st to end	Night	33% 8% 17% 30% 11% 2	2103
October	1st to 10th	Night	38% 6% 22% 27% 7%	3800
	11th to 20th	Night	40% 5% 16% 32% 7%	3886
	21st to end	Night	52% 6% 18% 20% 5%	4668
November	1st to 10th	Night	58% 7% 12% 18% 6%	2723
	11th to 20th	Night	59% 9% 16% 13% 4	2733
	21st to end	Night	54% 9% 16% 17% 4	2877
December	1st to 10th	Night	54% 6% 13% 19% 7% 1	3040
	11th to 20th	Night	61% 8% 13% 12% 5%	3751
	21st to end	Night	39% 7% 15% 23% 14% 2	5438

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	10% 3 21% 33% 27% 7%	180
	11th to 20th	Day	16% 7% 19% 27% 24% 6%	180
	21st to end	Day	11% 4 22% 40% 18% 5%	198
February	1st to 10th	Day	6% 5% 30% 37% 19% 4	193
	11th to 20th	Day	8% 3 28% 29% 26% 6%	270
	21st to end	Day	7% 6% 26% 31% 21% 9%	225
March	1st to 10th	Day	9% 5% 27% 37% 19% 3	393
	11th to 20th	Day	12% 4 28% 34% 17% 5%	460
	21st to end	Day	15% 4 25% 31% 19% 5%	506
April	1st to 10th	Day	12% 6% 27% 35% 15% 5%	460
	11th to 20th	Day	18% 7% 23% 27% 18% 6%	452
	21st to end	Day	20% 7% 26% 32% 11% 5%	544
May	1st to 10th	Day	13% 9% 23% 30% 19% 7%	653
	11th to 20th	Day	12% 5% 24% 30% 19% 9%	675
	21st to end	Day	18% 6% 19% 27% 23% 7%	734
June	1st to 10th	Day	19% 8% 25% 27% 17% 4	680
	11th to 20th	Day	22% 7% 20% 28% 16% 7%	680
	21st to end	Day	13% 6% 18% 28% 24% 11%	680
July	1st to 10th	Day	12% 4 17% 30% 26% 10%	671
	11th to 20th	Day	12% 5% 18% 31% 25% 8%	668
	21st to end	Day	10% 4 22% 29% 25% 10%	739
August	1st to 10th	Day	14% 4 15% 28% 28% 11%	676
	11th to 20th	Day	8% 7% 21% 33% 23% 8%	509
	21st to end	Day	11% 7% 20% 31% 21% 10%	539
September	1st to 10th	Day	14% 8% 26% 27% 20% 4	490
	11th to 20th	Day	21% 5% 22% 30% 18% 3	490
	21st to end	Day	12% 10% 29% 28% 15% 5%	477
October	1st to 10th	Day	11% 10% 27% 27% 21% 5%	300
	11th to 20th	Day	17% 8% 27% 30% 16% 2	300
	21st to end	Day	16% 10% 29% 28% 13% 5%	330
November	1st to 10th	Day	19% 5% 23% 32% 19% 3	297
	11th to 20th	Day	15% 9% 29% 33% 9% 4	234
	21st to end	Day	7% 8% 26% 41% 12% 7%	180
December	1st to 10th	Day	7% 5% 24% 39% 18% 7%	180
	11th to 20th	Day	12% 4 33% 32% 17% 3	180
	21st to end	Day	10% 5% 20% 32% 25% 9%	198
January	1st to 10th	Night	12% 5% 27% 38% 16% 2	950
	11th to 20th	Night	12% 5% 26% 40% 14% 3	950
	21st to end	Night	15% 7% 29% 35% 12% 3	1045
February	1st to 10th	Night	10% 6% 23% 39% 18% 3	803
	11th to 20th	Night	12% 3 27% 38% 17% 3	744
	21st to end	Night	6% 4 21% 41% 23% 4	628
March	1st to 10th	Night	9% 5% 26% 42% 17% 2	760
	11th to 20th	Night	12% 5% 26% 39% 15% 2	760
	21st to end	Night	14% 5% 23% 36% 18% 3	836
April	1st to 10th	Night	11% 4 27% 38% 18% 1	571
	11th to 20th	Night	15% 4 27% 36% 17% 2	563
	21st to end	Night	18% 5% 23% 38% 15% 2	570
May	1st to 10th	Night	15% 7% 25% 35% 17% 2	496
	11th to 20th	Night	14% 5% 21% 38% 19% 3	374
	21st to end	Night	16% 6% 19% 34% 22% 3	411
June	1st to 10th	Night	20% 5% 20% 35% 18% 2	380
	11th to 20th	Night	22% 6% 17% 30% 23% 2	380
	21st to end	Night	14% 3 15% 34% 29% 4	380
July	1st to 10th	Night	13% 3 15% 39% 29% 1	370
	11th to 20th	Night	12% 2 15% 43% 26% 1	368
	21st to end	Night	8% 4 16% 39% 27% 5%	416
August	1st to 10th	Night	13% 2 12% 36% 31% 5%	378
	11th to 20th	Night	10% 2 19% 42% 25% 3	559
	21st to end	Night	11% 4 19% 42% 23% 2	627
September	1st to 10th	Night	17% 4 22% 35% 21% 1	570
	11th to 20th	Night	16% 3 19% 44% 17% 1	674
	21st to end	Night	11% 4 28% 39% 17% 1	760
October	1st to 10th	Night	16% 4 27% 39% 13% 2	760
	11th to 20th	Night	14% 4 28% 36% 16% 3	760
	21st to end	Night	18% 7% 30% 32% 13% 1	959
November	1st to 10th	Night	18% 4 26% 36% 13% 2	973
	11th to 20th	Night	15% 4 29% 34% 14% 4	950
	21st to end	Night	12% 5% 34% 36% 10% 2	950
December	1st to 10th	Night	13% 5% 28% 33% 17% 4	950
	11th to 20th	Night	13% 5% 28% 37% 14% 2	950
	21st to end	Night	10% 3 25% 38% 19% 5%	1045

Page generated at 2024-11-07 04:55:50. Version ac07

Copyright © 2024 Attilla Danko.